worst service

i had a contract from mtn where they offered me 2gb which i was paying R208. between june or july i received a call from a call centre saying they are increasing my 2gb to 20 with no extra cost. they said i will be paying R108 only to find out they charge me R1000 Since from august have been enqiuring with them with no success they only gave me reference numbers.never communicated with me unless they call me. september i went at westgate branch also the lady that helped me send them an email till today i have not heard anything from them, mtn has never called me ive been the one who calls them what is very frustrating is a call center you dont speak with one person you find different people where you start your story from the beggining every time. now they have handed me to debt collectors and blocked my number,