I had the same with orange. I've switched to T mobile on their flex T service. It was the best at the time but orange have come back with these dolphin services which are bloody good.

There is one way to come back to orange as a new customer and therefore get the better treatment you do as a new customer:

End your contract and ask to have your number switched over to a pay as you go service. Keep the PAYG for a month or so, then sign up a new deal on the contract service you wanted. Then ring up and get the PAC code to transfer your PAYG number (which was your original contract number) to your new contract