bobbbbby,
go to qtel and say that your unlocked phone is unable to capture qtel's network if they won't help you (as I suspect), go to Mac in City Centre and tell them that your UNLOCKED phone is not capturing Qtel's network and ask them to have it checked by the specialized technician. It won’t be that costly and they have always solved my bugs with Mac products.
The max I have paid was 100QR.

If you cant still solve your problem. Wait until you go back to your country and go to any Mac shop. They will be pleased to help you with a smile.
Good luck

PS. Just a last advice: never ever buy 2nd hand gadgets again.