Someone is *****ing my airtime daily!

Hi Vodacom, please be of assistance with regards to my airtime. I changed my number a few months back on a prepaid service because I was getting an insane amount of spam calls. But the last week or so every time I load airtime someone takes if off, I get messages from a certain number saying you are subscribed to this at 5 rand a day and some 10 rand a day, these are all from the same number but from a huge amount of different subscriptions which I promise you now I have never subscribed to a single thing with this number. I am very careful with this number but now I cannot load airtime because it's instantly taken away. It's really frustrating. This has to be some sort of ***** and I'm not putting th blame on you, but I need help in getting my airtime back. And I need help with you blocking these people taking my airtime. I would love to know who they are because that's a crime and is totally unacceptable. Please assist me with this. Thank you.