Billing Query

I took out a contract sometime end of April 2015. At first they did not want to grant me one as I had not had a credit record until they saw my pay slip (greedy much?). Anyhow, got the Samsung S6 Edge (very faulty and I've brought it up with them and they put it down to a software upgrade issue. Been in for service about 3 times. Ridiculous). I took out the contract and the gentleman assisting me didn't bother to explain the ************ concept of an open line !! I was initially paying R700 p/m but every month it went up and up and up. I noticed this and limited the usage of the phone but it seems the less I use it, the more I'm being charged. I eventually switched last month to a uChoose where I pay a fixed R250 p/m (for no surprise charges and peace of mind). I did not use the phone for almost a month. It's been off but some how I'm being charged a R1000 for the month ! I'm very disgruntled. This is wrong &amp