Bad service and billing

I contacted the call centre before my contract ended November 2015 and they said if I don't cancel my contract I'm going to R99 every month.End of December I checked my invoice and I noticed that a add on internet bundle of R349 was added to my account. I didn't give permission for the add on internet bundle. I queried that on the 30th of December 2015 and its March 2016 and I didn't receive any feedback yet.