Well that was a positive experience.
It was back in six days with a new part fitted, and no charge. Online tracking so you can see where it is at the service center.
It was returned factory reset (as advised) and relocked to the network (still got the unlock details thankfully) and as per when I first bought it, the APN settings needed fettling to get mobile data working on EE.
Going via the Vodafone shop was a little complicated as they needed a Vodafone phone number otherwise the computer wouldn’t play ball, thankfully he was cool with this and used the ‘shop mobile’ phone number! Saved the hassle/expense of posting an expensive phone and being around to receive it when delivered back.