FNB SIM CANCELATION

I recieved my fnb sim on a friday and the next Monday i called to cancel and i was told i can only cancel by sending fnb an email which i did, its now Thursday and i havent recieved any responce from them. Can someone please call me urgently to cancel because i CANNOT stand the terrible network, i want to move back to my vodacom. Fnb data service is sky high and i cannot purchase my power hour and do many other things i could with my vodacom network. I Want to cancel and port my number back to vodacom like yesterday!! Please call me today!