Telkom *****ed up my Business telephone line

I transferred my business line from my old office to my home office, since the transfer I had nothing but major problems with my business line. The first problem was a very noisy line, I contacted Telkom numerous times about this, received many ref no's, email them, none of the proper means of communication fixed the problem, the line eventually went DEAD - no DIAL TONE, this happened for around a month. Telkom apologised for the inconvenience and credited the account and promise the line will be sorted out. A day or two later, I get a sms telling me the line has been restored, however in reality it remained dead - tried 3 different phones. I rep**** back to Telkom SMS and contacted them, the situation did not improve. I eventually had a enough and decided to cancel the line because it became a big problem with my clients complaining that they couldn't reach me. A couple weeks later, I get a bill from Telkom asking me to pay for the days the line remained dead. I wasn't prepared to pay for services that were not working. The line NEVER came back on, now Telkom handed my account over to their attorneys and eventually debt-collectors, they are now harassing me. Please help.