Poor workmanship and repairs

I called SA Waterproofing to repair a leaking roof. They say they have over 27 years of experience so I thought they know what they are doing. Within a year of the repair, the roof started to leak again and the repair they did has resulted in more damage. I reported the leak, the team came out and adjusted something and the next rainfall, it leaked again. My ceiling is now damaged. I have to constantly call them to come and fix it and get told they will discuss it at the office. I asked about repairing the ceiling and was told their repair man will come sort it out. The man came, saw, assessed and never returned. As soon as the initial repair was done I got constant reminders to complete the payment but I do not see the same level of urgency.