Vodacom overcharging!!!

My 14yr old daughter has a cellphone contract with Vodacom, which I pay. The original contract is for +-R400 per month. A couple of months back, i realised they were deducting over R600 on my debit order. I contacted Vodacom, whereby the lady operator investigated and told me there was another cellphone number ported to my daughter's number. I asked her how was this possible, but she could'nt explain. The number when i dialled said, number did not exist. She (operator) also said that there were no calls or anything going on, on this number. She did however say, that this had been going on since 2016. She gave me their ***** department's email address, whom I've mailed almost 2 months ago. But till today nobody from Vodacom has contacted me, and still they're deducting R200 more per month than they should be. Apart from me, i wonder how many thousands of other people out there, they're doing the same to??