HT5014 How to unlock iPhone locked to Orange/T-mobile UK

I bought this iPhone recently from ebay and contacted Orange Support but they said that I have to have account with them at least 3 months...

How I can do this now when even seller doesn't respond resopnd for my massages ?

I have to throw away this phone or there is any way to help me ?

Please let me know how I can resolve my problem...

Thanks a lot

Darius