Keyfob not working after having been on hols

Yesterday we came home from a week's holiday in the sun.

When I tried to unlock the car with the keyfob there was no action whatsoever! The same with the spare key that my wife had kept in her handbag all the time.

The driver's door unlocked immediately using the 'mechanical' method, and we and our luggage got in without further issues once the key got into the ignition and all doors unlocked automagically.

What can cause this? The fobs are quite battered and could do with a new cover that has the symbols on it. The batteries are new, and the fob will 'learn' the code again.

Or is it a Convenience Module fault? I had it programmed lately to automatically lock when approching 10 mph yet it has lost that feature as well.

Lucas