FNB Sim Card

I was given an FNB sin card inside Greenstone with the impression that i will get a discount when i buy airtime. i accepted the sim-swap and own it for about three years. From late 2017, there was an unauthorized deduction from my account of about R393,00 for airtime -top up. when i call FNB connect they could not help me, because they insist that i signed or contract or someone called me. They could not give me voice recording or a signed contract. After several attempts they said i need one month notice to cancel the agreement, which i know nothing about. They finally agreed to cancel on 01 February because they refused to fund me my money for January 2018.

This smells like an FNB ****, where they give customers airtime without them knowing it