A frustrated couple claims their basement flat is “being invaded” by tourists after their nightmare tenant illegally sublet it on Airbnb.

Yasmina Mathias, 62, and Robert Mathias, 74, from Chelsea, West London, have seen hoards of holidaymakers turn up to the property, at all times of the day and night. They claim they have even had to put a warning sign up by the flat in a bid to reduce the overwhelming bookings.

Now, the couple have to pay legal fees to try and evict the tenant and said the issue has caused a potential £25,000 loss in their finances. Yasminna and Robert said the “awful situation” means that retirement is “out of the question”. The ordeal has caused them an immense amount of “stress” after they spotted their property on numerous holiday websites.

“My health has really gone because of this, because of the stress. I’m constantly thinking about it. I’m worried. We have a mortgage to pay,” Yasmina said, speaking about the ordeal. The couple works from home in their flat. Yasmina runs her own tarot card reading business while Robert manages an IT firm. Both said they no longer feel comfortable in their home due to the constant strangers they claim are turning up in the basement flat which they also own, and feel they have to double-lock their front door, reports MyLondon.

They also accuse the estate agents Marsh & Parsons and RightMove of negligence, claiming they both failed to carry out in-depth reference checks on their tenant. RightMove said it has confidence in its referencing process and when issues arise, it works with letting agents to secure the best possible outcome for the landlord. Marsh & Parsons said it does not comment publicly on matters involving customers and their properties. The agency said it works diligently and directly with clients to help resolve any issues.

The homeowners have begun the process of evicting their tenant and are expected to have their request for a possession order heard by a court in December. By that time, they will have missed five months of rent, they claim. Robert claims he noticed something was wrong two weeks after signing a new tenancy agreement. The 74-year-old was at home when he noticed a family of four outside the property looking lost. When he approached, they said they had arrived from Mexico and had an Airbnb reservation for the basement apartment.

From that point on, people ‘streamed’ in and out of the flat, Robert claimed, adding that the tenant had also stopped paying rent. He said: “It’s really awful. Our home is being invaded. It’s like burglary but worse. I can’t even go in the back garden to prune the bushes, which [the tenant] doesn’t bother doing and we stopped paying to have the front cleaned.”

Yasmina and Robert claim their tenant has a ‘very organised’ operation which includes cleaners and a constant flow of guests. They claim he also installed a new smart doorbell which they believe he uses to track guests when they arrive and leave. The couple have become so fed up with constant visitors that they’ve now resorted to placing a warning on their front window. It says the basement flat is being sublet without their permission and that guests will be reported to booking agencies. The couple said the flat has also been advertised on holiday-letting sites like Booking.com and Airpaz.

The Local Democracy Reporting Service (LDRS) has seen these ads and also found the flat advertised on Vrbo. The ads boast of a two-bedroom lower ground flat ‘in the heart of Chelsea’ with a fully furnished kitchen, flat-screen TV and free wi-fi and are charging between £135 and £180 a night.

On Airbnb, the flat is described as a ‘charming’ and ‘stylist retreat’ in ‘one of London’s most prestigious neighbourhoods’ where ‘the perfect blend of comfort, convenience, and character mak[e] it an ideal choice for both short and long stays’. It is being listed for £180 a night and is reserved for most of October.

When the LDRS approached the host via the messaging portal on Airbnb for comment, they declined it. Airbnb then sent a generic email saying using the portal to solicit third-party services or other websites was against its terms of service and threatened to suspend our account if this was violated again. The LDRS also contacted the tenant via phone and email but received no response.

After being contacted for comment sites including Airpaz and Booking.com said they would remove the ad from their platform. Vrbo said it is investigating the matter and that as per its terms and conditions, hosts have to comply with legal requirements and operate in line with the law. A spokesperson added: “The incoming national registration scheme for holiday lets in England, which we have been calling for for years, will create the first comprehensive and authoritative database of properties. Once established, authorities will be able identify and address rogue operators effectively, which will mean that instances of illegal subletting can be identified more easily.”

Airbnb said hosts are ultimately responsible for ensuring listings comply with all legal and contractual requirements and urge them to check and follow the most up-to-date local rules while listing their space. The company said it is not an accommodation provider but operates a marketplace where hosts can list their accommodations. Where possible, it encourages parties to resolve issues directly with each other.

Where this is not possible, it facilitates a pass-through process and forwards communications from third parties to hosts. A spokesperson said: “We have been in contact with the host and landlord regarding this private dispute. We ask all hosts to ensure that they have permission to list their space and remind them to check and follow local rules before they list and throughout the year. This is made clear in our terms of service and on our responsible hosting page.”

A Booking.com spokesperson said: “All partners must agree to our terms and conditions, verifying that they are legally permitted to rent out their accommodation. In the rare instance that we are alerted to a concern about a specific property, we investigate immediately and can remove the property from our platform if necessary. In this instance, the property is no longer listed in our site.”