Deception - Price Match

I was advised by a booking.com agent to make and pay for a booking so that they would process a price match claim off their own app due to the app changing prices when i was booking. I sent through screenshots for verification and stayed on the phone with their agent who verified and assisted me to make the booking throughout the process. i was then told that everything is in oreder and after my stay, i should sent through the invoice to process the claim. i did so and after the stay they now changed the entire story to i did not have the correct currency despite me supplying everything before making the booking on advise from their own agent. Now i spend hours at a time on the phone everyday for the past 3 months to try and get back what their agent made me do!!!