Hi Tony
I presume the garage is not a jag specialist. I suggest you ask them for the fault codes they pulled from the car then post them here so we have a better idea of what the problem is. I would also get the battery checked properly. If you have the Stop/Start system you should have an AGM as the main battery which has a different voltage profile to a wet cell battery (12v at rest is virtually flat!). If you are only using it every few days for local journeys the battery will not be having a chance to re-charge. As with many modern cars these are essentially a load of computers each talking to the others over a network and they hate low voltages, responding with all sorts of weird errors. In the first lockdown I left mine too long and completely flattened the battery meaning the rear doors were permenantly locked and the windows did not work. All that was needed was a reboot using the garage computer 🙂
Regards
John