overcharged for NOTHING!!!

Hi,upgraded my 1gig laptop contract that I took out for my sister for her varsity,and there was always a carryover,I paid R359PM,now took out a 5gigday/night (10gig over a month) for R319 PM,upgrade fee R120,so I was expecting to pay atleast R500,I had the wi-fi at home for a week,line got cut,tried calling since 22 april,got through today,only to hear I owe them R2440.17,for internet that was used for a week,for varsity purposes,so I have been without it for 2 weeks now,and was told that the \capping"I had asked for failed and I wasn't notified"