Andrew's Roofing in Bishop Auckland

Did work on my mothers property. He was supposed to remove all ridge tiles, clean off old cement ridge tiles, lead flash the chimney stack, point in the lower 4 rows of chimney stack, and fit 6 roof vents.
From arrival to job finished was 50 minuets and the roof still leaks. When I phoned them they claim that it must be the roof tiles as there porous, and said he would call back out, no sign of him.