Missing Airtime from my MTN sim card

I did a sim card swap beginning of April with just over R600 credit on my prepaid sim card. They did the sim swap with no problem telling me to wait approximately 4 hours for the new card to be activated after which I got a message I must RICA the sim (Now this was only a sim swap to the same nr as the old card which was rica-ed) So I went back to MTN to do the RICA where I was told to wait for 24 hours before I can use the sim card. To my frustration after the 24hours expired I had to find out my balance of R600-00 plus disappeared from my account. so I queried it just to get the answer my air time was used to connect to the internet. I hardly ever connect to the internet via sim card as I use my Telkom ADSL uncapped data on my pc's if I want to connect to the internet as well as my cell phone. They stole my money with the lame excuse that my airtime was used for internet connection