Unauthorized Charger on contracr

I have my contract under Vodacom and use the app frequently, recently I have noticed a GB bundle added to my contract which was not authorized, further to that some sort of upgrade happened which was also not authorized which has set my upgrade date to 2 years from now with the other linked sim cards I have under this contract. How are you able to add items to a contract without my signature or consent? Looking forward to a speedy resolve on this. Thanks