Thanks everyone for the help but the problem is now solved. I took the phone into Carphone Warehouse and they managed to get it sorted. Seems that something was locked but it's working okay now. They advised me to move all my contacts onto the phone rather than the sim and then order a new sim from my carrier. Put it into my old phone using a converter and move everything back from the phone to the sim. I guess another option would be to move using bluetooth from the Samsung to the iPhone5. Thanks again.