Missing airtime and suspected *****

I have continuously been experiencing missing airtime whenever I have airtime remaining that I purchased. I had about R30 airtime left and now I have no airtime.

I queried this when I contacted the customer care line and through chat but I got no assistance. I then got a detailed breakdown of my costs through the self-service option when I selected the option when I called in and the charges and transactions that I saw were not mine. I suspect that someone else is using my number. I am also getting messages with regards to payment notifications from DStv from this number but that is not the number associated with my DStv account.

I want this to be looked into and rectified as I donyknow what is going on here.