@Dccoxswain I'm so sorry about your recent experience, if a bill is produced before a change of contract takes place we don't issue an amended bill but what happens is you get a credit for the difference on the following bill. This is the same for everyone and we can't change that but it should have been properly explained to you and it sounds like the advice provided has not been great and I'm sorry you've been disconnected again.
The mod team are busy at the moment so it would take us a day or two to get back to you if you send in your details on the click here to contact the mods link. You can find that if you click my username.
Alternatively if you need to speak to someone urgently about this I'd recommend our billing live chat team who can be contacted on this link.