customer service supervisor laughs at harrasment

My mom has a new contract for a tablet and from the first day has been getting calls from an unknown nr. When we called to ask if they can investigate we received no help and when we asked to speak to a supervisor nomsa kwezi she actually laughed at the problem. Im disgusted at a supervisor laughing at something like this. And who do we then complain to when the supervisor behaves like this. <br> <br> I will be looking in to cancelling her vodacom contract as well as the two i have and move to a different operator as vodacom clearly doesnt care about thier customers.