Vodacom is ripping me ofg

In the last 4 mths, I have lost airtime ( R20) a time to having subscribed to games which I did not. I have phoned Vodacom 4 x in connection with this. They will stop it which doesnt happen then I trans R320 airtime this wk for 2 x 1gb bundles. R20 was taken from my airtime which I wanted to use for phone calls. I cant afford this. No answer to explain this from Vodacom. I will not transfer any more money to my phone from my bank. I will buy it in the shops. If this continues, I am cancelling my contracts. I have bee a client for 18yrs which seems to count for nothing.