Mobile telephone - Importing and registering (Istanbul)

Hi everyone, I moved here in May with my prized Nokia phone. I purchased a pre-pay Turkcell simcard and number. After two weeks or so the phone stopped working. So back to Turkcell and was informed I had to resister the phone which will take 10 days or so. - No probs and soon after the phone worked normally again.

This month (Nov) I upgraded my UK mobile phone account and purchased a brand new phone at Heathrow Airport. So as soon as I landed back home in Istanbul I went to Turkcell to register this phone before it stops working and was politly told that I cannot register another phone for 18 months - Only one every two years !!

Surely someone, somewhere is mistaken - any ideas or help so welcome.

Cheers

Kev...