No help from Customer Care

I made a booking in January 2025 for the 4th of April 2025, 3 months ahead of time as I knew accommodation would be limited in Cape Town in April due to the Two Oceans Marathon. I booked a place close to the start position so that travelling wouldn't be an issue. I paid immediately after booking. 2 days before my trip I received an email from booking.com confirming my trip. On the 4th of April I arrived at the guesthouse at 16:00. On arrival I was informed that my booking had been cancelled and there was no available room for me! They informed me that they received a mail on the 21st of March from *** saying that the traveller had cancelled the booking. I definitely did not cancel!!! This left me in a horrible situation trying to find accommodation last minute that was still close to the start point of the race that I would be doing the next morning! I eventually found another hotel, that was triple the price!!! I am very disappointed in bookling.com. I have been a loyal client for many years, but to date I have still not had any feedback regarding a refund for the first accommodation that was booked and paid for.