Just been down the dealership.
At first they claimed that they wouldn't have had to take the battery off when they did the work?
They clearly had as my Radio was security locked and needed a code when I picked it up.
Anyhow after speaking to a technician the lady said the battery may have been disconneited and run down over the time that they had, had it. I've now got to take the car in, leave it with them while they charge the battery for 24hrs after which they'll do a battery test.
I get a courtesy car in the meantime.
I agreed to this, but TBH this is just nonsense. It's causing me more hassle than it's worth, so if I can find a suitable battery I'm probably better off just getting a new one