Ridiculous service

So i bought 2 contract phones from vodacom and I receive airtime every month. I just use the cards to make phone calls thats it and switch them off once it finished. The sim cards just stopped working i think in january. Then decide to do sim swop today and the other one had no airtime and the other one had like R60 something. When i phoned was to I subscribed to something that takes R7 per day and thats shocking cause I don’t use the cards. Im just frustrated by vodacom and even to do sim swop was charged when the cards just stopped working on their own. This is just ridiculous and unacceptable!!!! Cause there are quick to debit the money while they cannot do the right thing .