Mr price sim

With my account I got a Mr price Sim card, thaught it's nice because I could take airtime whenever I needed it, I took alot of airtime on my account when I started realizing that after taking airtime when I wanted to make a call it says I don't have airtime available, so I decided to record it with my other cell, I took airtime and then straight after I would check my balance and it showed R0, then a few days after I checked my account transaction and it showed that they charged me for the airtime but I never got it, so they have been robbing me for almost 2 years and only now I realized it. + when sending messages to enter competitions it shows that the messages go through but when checking my airtime balance it never deducts airtime which means messages did not go through.