Can you assist me i want my refund because the laptop it was still on guaranteed when i took it back to the shop

I bought laptop on the 4th May 2023, it gave me problems i bring it back to OK furnutes on th 20 July 2023. It been quiet since i decided to do follow only to find out its still at the shop the send it to supply on the 10th August2023. The problem they come back telling me the supply cant refund the laptop because its been used for 4 month of which it was only 2 month with me