BROKEN TV Lost slip

I bought a 65in Hisense TV from game in December 2018. On the day of the start of the national lock down (27 March) the TV image stopped working. This is still within the 2 year period and we lost the slip so contacted game Somerset mall for help. The manager Peter Bos an attempt to help us find the slip. After supplying all my credit card statements indicating the date and value of the sale, we can only be helped with a bicycle slip after 6 months of queries, emails and phone calls. All I want is to send my TV to hisense so it can be fixed under the two year warrenty and time for this is now running out. Can anyone help me please!?