If that's the case, it'll be the PSU killing it most likely, but it's very unlikely. I suspect more that someone in the shop your brother used to get it fixed told porkies to rip him off. I only say that because I've heard loads of shops doing the same scam. They charge the RRP for a drive they paid trade for, wack it in in about 5 minutes, charge an hour or more for labour and reinstall windows. Often the only thing that went wrong is that windows shagged itself. If it really is killing drives, then it's at least 2 years old and not worth replacing the PSU or the motherboard (unlikely to be a motherboard killing an HDD if you ask me but it's possible). Personally I'd just spend £300 on a new one in the sales.