Double charge for insurance

I contacted Vodacom on the 7th of Sept regarding a double charge I found on one of my accounts for insurance. Small amount but compounded it adds up to a lot. I got a reference number and no further response. I then followed up again today and was told I need to speak to the insurance department. Eventually a lady helped me by stopping the one payment for insurance but tells me that they don't know who added the extra insurance and therefore cannot refund me for the overcharge. This is scary! People should carefully check their accounts on a monthly basis - a couple of rands every month adds up to a lot of money that Vodacom is taking from you without your consent