********** data charges on my account

I am charged for data bundles on my account, I was told that these are bought through Just for me specials, I do not use this service! I was told there is nothing to be done but to change my contract to a pay as you go, I did that with the the number, but I am still charged for data bundles, although I can’t buy these from this number because I never have airtime available, please explain how this is possible?