Support SIM Car Error

I'm getting Sim card errors on my S3 "Sim card removed unable to contact mobile network please insert valid sim card and reboot. "
I've replaced SIM 2 times replaced the reader, tried the rub with cloth, stuffed paper in reader to get better sim connection and finally tried a few strips of tape on back of sim and still get the error. . i now live in a different country from where i bought the phone and Samsung will not help as they claim there technician can not work any model other than ones domestically purchased. it will cost me a fortune to ship the phone back to Canada for the diagnostic... the phone is now a $600 paper weight on my desk Can anyone help with this issue .. bTW the only consistency i can tell is that the error occurs when signal drops ( no bars)