BAD Company!!

My goodness!!!! What a poor company to do business with!! After we have installed this system in our offices we have had the WORST help with lines that are faulty! We have been struggling since Jan 10, 2019 to get someone competent to come out to the office to assist us with the lines. Then when finally the person came he told me it was Telkom. Telkom came and proofed that the fault was not on their side. Again, I contacted Telelink. Later on I started writing down dates and names. I made numerous calls but no one responded, and every time it was promised that a technician would come to fix the problem. I am completely fed up and do not know what to do. We are losing business because we cannot take calls on our incoming lines. We still have a 5 year contract with them. Can anyone give some advice regarding this situation?