FINAL UPDATE: finally got my car back from the dealer yesterday after 6 weeks in the garage. HondaUK have changed the main battery and all seems to be working as it should. One part of the dealers workshop looked like a crime scene with the old battery now crated up and cordoned off with high vis tape. This will now be whisked off to Swindon to be dismantled and examined to see if the fault can be identified. As a side note I’ve quite enjoyed driving the MG4 that Motability arranged for me although it is a bit low but has been fun. Fingers crossed I will have trouble free motoring from here on in.