On Friday, 14 May 2021 at 19:21:18 UTC+1, JoeJoe wrote:
Trying to buy a replacement battery for an old Samsung Galaxy S7 phone
that is nearly dead.

There are plenty on offer on eBay at around £5-£7, inc. all the tools
required for the job and free delivery.

I can't comment on the postage aspects of your question but having recently changed the battery in my Samsung S6 (different phone obviously but very similar) I was beginning to get very frustrated at reading such mixed reviews about 3rd party phone batteries - many of which were seemingly fake Samsung batteries. I stumbled across Green Cell who are a legitimate manufacturer of batteries and sell direct. They do one for the S7, and whilst it is more expensive than many on eBay at £14.95 including delivery I think the extra is worth it for peace of mind. Thought I'd share this in case it's of any interest/use.

https://greencell.global/en/samsung/...-s7-g930f.html
Company info: https://greencell.global/en/about