Serious integrity issues with Booking.com

We made two bookings and after paying the full price for the one, I inadvertently cancelled the wrong one. I realized this immediately and messaged Booking.com and the home owner to reinstate the booking. The owner said no problem and copied Booking.com. The next day the booking still showed as cancelled so I called the Booking.com Call Centre and spoke to an agent. The agent said that the home owner must agree as they could not reverse a cancellation (why not? - this is the catch). The owner messaged them again that the booking was good. Booking.com agreed that the message had been received but refused to reverse the cancellation stating that the system does not allow for cancellation reversals. No problem as we went to the accommodation and had a great stay. A month later the homeowner contacted me and said that Booking.com had never paid them. To cut a long story short, and after lots of messaging, it would appear that Booking.com saw a gap and have kept the full payment for an expensive weeks accommodation and never paid the homeowner. They now refuse to take their calls. This is clearly a 'fine print' policy issue with cancellations and the homeowner contract. My advice is not to use Booking.com as they have integrity issues - any erroneous cancellation, quickly communicated, should be a standard systems function for reinstatement and at least ensure that the homeowner gets paid. Shame of you Booking.com - we will never use you again.