Battery was on 58% then it just switches off and shows a charger and a big battery icon when i try to switch it on. So I plug it in and after 10 seconds it's on 58% 👀 It's done twice today. Now it's on 27% and I've been using it for ages and it's not gone down .Any ideas ? It's 18 months old

My original Nexus 5 did this and i had to contact google and got a replacement. Never found out why it did this though.

Sounds like the battery is shot. Happened to the one on my Samsung Galaxy S2. I'd consider a restore to rule out software but if not you need a new battery. You can do the replacement yourself (good guide here: https://www.ifixit.com/Guide/iPhone+...lacement/21745) if not Apple can probably do it for you (does anyone know if Statutory Rights would cover this if it's 18 months) or some repair shop near where you are, which I guess is likely Wrexham

Wait it's an iPhone isn't it? Oops.

Nexus is 5X not 5C...