Shocking customer service

I am a reliant on my telephone line for business call out and standby purposes. After registering a fault more than six weeks ago, and despite numerous follow up calls to their service centre, my landline has been virtually unusable for more than six weeks due to extreme line noise and frequent dropping out, Despite repeated standard SMSed messages that they are busy rectifying a fault, my telephone service has since further deteriorated to the point that it is more often than not totally unusable. From the above it appears that customer service is definitely not viewed as a priority!