Duplicate payments - refund request.

I purchased a iPhone on Vodacom contract from Tygervalley Store for my granddaughter in December. The sales person asked if we want insurance which we accepted. However, my granddaughter said she will pay for it and gave the necessary details, I paid every month the full Vodacom bill (I HAVE VARIOUS CONTRACTS) and subsequently discovered that she paid as well. I have now written to the iStore and the additional insurer They confirmed that the additional insurance is being paid and active and advised me to contact the Tygervally iStore. I wrote to the manager Dawayne Jowell and the answer came back to contact Vodacom. I rep**** and pointed out to him that this is not a normal cancellation but that besides the cancellation I am looking for a full refund. No response. I have submitted all the necessary paperwork. Pleaser can you help.