Missed calls - Pretending to reach me

I took out a policy with Vodacom. After I did some research I decided to cancel the policy. I used the customer service email address provided for queries or cancellations to cancel the policy. I received no feedback in two days. After Vodacom received my emails one of their consultants have been giving me missed calls all the time. My phone only ring once. There is no time to answer the phone when it only ring once. When I do answer the phone the consultant pretends he can't hear me and there is nothing wrong with my network. <br> After that he continues with the missed calls.<br> Just cancel the policy and stop with the annoying missed calls