w900 prototype

hello
i bought a second hand w900 and after i flushed it in a privet store to have hebrew language it started to send sms to a number in switherland and when i call this number it says that my phone is a prototype and i can't do nothing about it to stop this sms, when i talked with the store they day that it is not from the flush because they flushed other w900 and there was no problem with them
i tried talk to the person how sold my this phone and he just vanished
meanwhile i change the servise number of the outgoing sms, is there somthing to do about it?
can it be from the flushing?
that can i do?

Why dont you buy a phone on ebay? it's quite sheap :)

I didn't know, that a w900 exists

well, it could be a BLUE one, like the most of us have RED phones, you could have buyed the phone from a TESTER and he had the phone for testing(cos the tested phones remain to the testers). So you've been screwed. Try to resell it, is the only thing I could say.

have u tried reflash the EROM by using toolbox help which u can find in 3rd party phone service provider? If still cant be help u can consider of changing a flash card in the phone.