STUGGLING TO CANCEL VODACOM CONTRACT

I Need to cancel my contract and I am out of the country. I asked my sister to go to the vodacom store in Cresta and find out how I can cancel my contract while being out of the country. I am sure there has to be an email address which allows you to cancel. The consultant Aphiwe from the Cresta store said he cannot help as he does not know the process to cancel. This shows that the Vodacom consultants do not have sufficient information to help their clients and instead asked my sister to call the help line. PLEASE LET ME KNOW HOW CAN I CANCEL MY CONTRACT WHILE BEING OUT OF THE COUNTRY????