Mountain Lion not available in UK store

My iMac completely crashed and was not recoverable via Disk Utility. I managed to copy my Home folder and reinstall from disks (which has put it back to Snow Leopard). I read lots of posts about Mavericks being unstable and causing lots of hard disk crashes similar to mine and I also found it slow and sluggish.

Therefore I'd like to redownload Mountain Lion which I purchased last year.

It shows under my Purchases on the App Store but when i click on it I get the error "The item you've requested is not currently available in the UK Store".

Please can you let me know how to download the software as I bought and paid for it.

Thanks,

Antony