Londonrentalflats.com review: Vacation rental

Online booking of vacation rental. We live in the usa, planned a trip to london. Arrived in london, had no address of said flat, we were suppose to me met by driver. Called Carl he made an excuse and 20mins later a cab driver picked us up. 15 mins into the ride Carl called and informed us he was putting us in a different flat. My husband is disabled, during booking process he informed Carl that he needed a very comfortable bed. Carl assured him the bed was comfortable. Arrived at flat it was dingy noisy and bed was awful. My husband could not sleep in it. That morn he called Carl and asked about bed in the flat we originally booked, Carl said they were exactly the same. My husband told Carl we would not be staying at his properties and wanted our money refunded. We have been back home a week and they refuse to refund our money. The reason is because we said bad things about the flat. We don't know who to contact in london to get help? We have our bank and paypal on it, hoping to get our $5000.00 back. Also we never received a rental agreement. Internet search revealed many similar stories.