Blocked sewage drain.

My daughter lives in Surrey Estate and has an ongoing problem with blocked sewage. The City comes out at least twice a week to sort out the drain which is excellent. This has also led to the collapse of a small section of the road. The council again fixed the road in record time which is great. They fixed the road twice yet has not sorted out the problem which is causing the blockage. This makes no sense. It must be costly coming to clear the drains and fix the road. But they do not sort out what causes the drain to block. We are suppose to have the best City but this boggles the mind.