My phone - the Sony Ericsson K800i, I know is a bit ancient but it suits me for my needs, requires a new battery but I can't find one anywhere apart from ebay. I did buy one from ebay but it wouldn't fully charge so they sent a replacement. The same thing happened so they refunded my money. Do any shops sell phone batteries now?

Shops carry a limited supply of spare batteries, but usually only for current models. It's unlikely you're going to find a bricks and mortar store that's still stocking batteries for a 6 year old phone.

This online store claims to have them though:
http://www.mobilefun.co.uk/sony-eric...t-33-p8838.htm Best to ring them to check they've got stock though.

Thanks, looks like that's my best bet.

I would question the condition of any battery that has sat in storage for about 5years.
But saying that I have always found mobilefun to be an excellent online store with very quick dispatch and delivery.