Rsaweb dont do it

Once again.... account query - charging me R1400 and odd rands for a service that's not even working for a week. Phone account dept. 15min later, still nobody that can help me. Charged me for modem and installation fee and a month's internet started billing from 15August where I clearly requested billing from 1Sept. Installation fee - me myself and I installed it.... starting service (requested from 1Sept, but there was an issue with vuma) so I was officially activated only 6 Sept..... now they want to suspend my service for not wanting to pay for things I never received.... and 15min later... I asked them to phone me back in 5 Min when I will have a bit more time to be able to speak, since I'm at work.... and they can't even do that ...... How do I cancel this service without paying an arm and a leg....i can't deal with bad service