technicians broke internet and have excuses when instaling a new line

these company manages the technical aspect of out fiber connection in our complex and on Friday 26th June there was a new installation on one of the units which we suspect could have affected some of the existing users. when we raised the line being down with the technicians that were on site they said before they leave it would be resolved. they left and our lines were still down. we then logged calls with vodacom and even explaining the scenario they still insisted making me go through the trouble shooting process. on Monday we tried to follow up on the issues we even had to liaise with the unit that was having a new installation and the technician sent defending messages and said that he did not break the lines that the issue was with the DFA feeder and that he was not a chancer and that it was a coincidence. surprisingly the lines went down as they worked on the feeder on our block and not sure what they were doing as the other block has its own feeder. the excuses and lack of urgency are very upsetting