Complaint a bad service

I have a problem with the PC shop based in Berea no 23 Pearce street Berea in East London I bought a new printer last year for an amount of R12050.00 on the 30th of September 2021 now last month now they don't want to fix my printer and telling me that the part that is damaged is not under warranty and been giving me different reasons and today they told me that they were not wrong for not telling me that I must not use any other cartridge so there's nothing they can do and it is not even a year since I have bought this printer and I am behind with my work because I use it alot. I told them to give me back my money or fix my printer and also they always tell me about their suppliers and I don't care about their supplier I bought this printer from them not from their supplier.