Hi, to be honest it's very very rare that they just stop working, there isnt much you can do to fix it "I dont know a way" the actual remote isnt very expensive it's around £45-50 mark and you don't need a new key blade, and 25 mins labour to code the key, you will need both keys to have this done other wise the spare key wont work as the code has changed.
Hope that helps!
Jack