Bad customer service

Hi guys , please advise me I bought a laptop (lenova)at hifi corp secunda I bought it in February this year.I only used the laptop to write my assignments and when I’m done I will place it on safe place until I need it again to write my assignments I started noticing that the laptop is very slow and this time around I was writing a assignment it went of it decided to take it back to the store late may/june .I explained everything what’s happening with the laptop and the told me that she will book it and technician will look into it , and I will have to pay the cost of fixing it if the laptop was damaged by me (which I did not) unfortunately the results came back and stated that i caused the damage I have to pay for a repair fee of R6000 while I bought the laptop at the cost of R4000 I refused to and told them to bring my laptop back ,now I’m told I have to pay a rejected fee to get my laptop back,Mind the lady that called never spoke about rejection fee and I was never told about T&Cs in black and white to go through it and sign, now the sore manager said that which means I have lost my laptop because I am not willing to pay the rejection fees.

Please assist what must I do?