MTN airtime dissappear

bad service, had a router contract with them and it expired last month. I terminated the contract and switched my sim to prepaid and never used the sim card until today when I decided to load a once off data. I loaded R140 airtime but when I checked balance it was R24, I called mtn about the issue and they told me I have game subscriptions that I don't even know. they couldn't help in anyway but to cancel the subscription. this is nonsense because they subscribe these ******* on our behalf and expect us to account for this.