Originally Posted by scoob101
I`ve just been down to the 3 shop, and they won`t accept the phone back, because its been unlocked, funnily enough they didn`t mention this when I bought the phone and told them I`d be using it on O2.... I`ll speak to trading standards as well.
If you bought it in store and it's not faulty and is fit for purpose then they don't have to do anything as far as I'm aware. If you bought it remotely (online/phone) then you can return it without giving a reason within 14 days.
But since you've unlocked it that returns guarantee won't apply anymore as it's not in the condition it was in when sold. Your only grounds would be a fault or not fit for purpose, and the purpose was to work on the 3 network which I assume it does. And in neither case would they be obliged to give you a refund, just a replacement (which presumably would be locked to 3 again).
If I were you, I'd ask your preferred service provider (the new one) to re-flash it in their service centre, as that'll probably be their version of the firmware with their MMS settings. There will probably be a charge since they didn't supply the phone.
Have you checked if the Samsung Diagnostics tool can help you out?