nightmare with pc world repairs now they are saying a malware problem no idea what I

My netbook has been playing up for a year, since November PC World have replaced the hard drive 3 times and still not able to use it. I had to go and buy a cheap tablet just to have internet contact.

So in the last month they replaced the screen, bezel and back then lost the cable.
When we got a replacement the network wouldn't even turn on so straight back in repair. Comes back with a new hard drive but barely functions. They were going to write it off today but wanted to do some system tests over the phone, now they have decided its a software problem and its to do with malware, so not covered and won't write it off now. Firstly can they be 100% sure over the phone it is a malware problem over the phone ? They made me go into several screens and it was something called PC Backup which has them convinced. So their advicr was to phone Acer And pay £52.00 for a systems restore. No DVD/CD drive. Can't afford it and not worth it anyway as its nearly 5 years old and battery went years ago but I need a laptop as the tablet not compatible with the wireless printer.

Is there anything I can do without paying Acer £52 to restore the system ? According to PC World its the malware that is causing the problem. They may as well talk Martian to me.