Ignored for 8 months

Our business took out a top up contract in November 2018 and received a R28879.37 bill as it loaded as an open line. We have made numerous calls, logged several disputes and still get our lines disconnected approximately 2 times a month. Our sales reps can't work with no phones. We are ignored by the account manager and the regional manager tells me that they are waiting for a response from head office... it has been 8 months now