Play Store Problem

Basically im from the UK and my network provider is EE. When i go to the playstore to purchase a item it says o2 billing and since im with EE i cannot make any purchases ive tried to remove it howevrr i was not lucky i tried to add EE still diddnt work. Can anyone give me some sort of tip and advice on what to do cause this is causing me alot of problems.

Thankyou for spending time to help and read this thread.