Low battery voltage throws up all sorts of problems, some obvious (no S/S, no HRW etc.) and some less so. I would suggest you put it on charge yourself for 24 hours or so and see what happens. Dealers tend to respond to these issues by charging the battery, whereupon the problem magically goes away and they can send you away happy(ish). Problem is, it will come back......So, finally got my car into the Glyn Hopkin at Chelmsford today, after a 2 week wait ( I was sweating after Boris' last night announcement) and they could not find a fault!
I told them that I get a loss of acceleration every day, usually after sitting at a junction or traffic queue (the engine revs, but it pulls away really slowly), so they went away to have another look and reported back that the next step is to take the car over night to charge the battery. However, they are now closed for at least three weeks!