Ridiculous mobile data disappearing

I am having challenges with Telkom mobile data. I have a contract with them, they load 10GB every month and now this month already 5GB is gone, how so, I don't know. Funny enough I have another sim whereby they send me 1GB every month and that 1GB is not yet finished. I have been trying to get hold of their call center for clarity, they play me a song to say that all their consultants are currently busy, mind you I have tried that more than 5 times. Is there anyone else out there shouting with the same situation?