Unexplained disappearance of minutes and added amount

I have a smart 50 telkom mobile contract, and recently I've been charged for calls I've never made, like how a 50 minutes of calls magically turned to 1 minute, without calling anyone, as I can see my call history, and on top of that my bill for August comes with a added R132 for calls to South african numbers, when clearly my contract is capped to 50 minutes.

Please stop taking me for a fool and sort this out.