Q: my phone is locked to t mobile and T mobile are unable to unlock it as I am not the original owner!  I have sold the phone and user wants to use Vodaphone but cant get the phone unlocked by t mobile? any help please.

Bought an Iphone 4S off Ebay site two years ago.  It was a new phone but with T Mobile/Orange.  This was not a problem as was going to be using a T Mobile Sim Card.  I have since sold this phone.  The person who has bought the phone wants to use a Vodaphone sim card but the trouble I am having is the phone is locked to T Mobile and because I am not the original owner of the phone they are unable to unlock the phone!  The only way of getting this phone unlocked is paying £99 to a company T Mobile have suggested. 

Does anybody have any suggestions?