bearnecessities sorry to be the bearer of bad news, but not long before Comet met their end, they were busted by M$ for punting PCs with dodgy Windows recovery discs.
You may well be one of the victims if you’ve done a recovery from a bent disc – I think that’s how it would work.
If you contact M$ I suspect they’ll still try and flog you an upgrade, but the fact that you may well be the unsuspecting victim of malpractice by one of their premier re-sellers should do you a favour in terms of their offer. I’d certainly point out the fact that you trusted Comet to supply kosher gear as they covered their stores in M$ branding.
Hopefully they’ll do the right thing.
Good luck.
Here’s one link to the original story:
http://www.pcpro.co.uk/news/371992/comet-sold-94-000-counterfeit-copies-of-windows