OVER CHARGING

IN A NUT SHELL....Have a contract with MTN every month bill is around R700. MTN sends me a new LTE sim card in the post. ( I did not ask for it) DId a sim swop to the new sim. same number. Now my bill is R3000 and R2200. I have called the 808 number but no one can help me. I need some one from the accounts to give me a call. I have spoken to a attorney and they do say I have a case. But I would like MTN to first contact me before going that way. MTN please contact me URGENTLY.....