Shop refuses to give me a refund

I bought a Hisense TV on layby when it was on special for R12999.90 in November 2024. I managed to pay it off on the 25th of March 2025. Instead of getting my TV, I got a story that the price had now increased to R17000. I did not have the money to pay the difference as they had promised me that the price will not change. I then requested a refund but the shop has not been helpful at all regarding this process. I have been struggling for months now and I just want my money back please.