Key fob repair

Hi, I am the owner of a Paceman to be precise.
Unfortunately a few weeks ago the key fob (round part) detached from the actual key without me noticing whilst I was crossing a road; once I realized I had lost one part of my key I traced my steps back and I was lucky enough to be able to find it in the middle of the street.
Few cars had run over it but for two weeks after this happened all three lock/unlock buttons were working just fine. One by one then slowly stopped working over the course of week number three.
Before buying a new key from mini (for £160) I was wondering if there could be a diy way to fix it.
Can you help? Or do you know of any other mini blogs where I could seek help?
many thanks in advance for your help.