If the tiles are popping out, you should seriously think about what else did the thekedar do wrong. You might want to do a complete inspection of plumbing, electrical work as well. Sometimes, the issue is that labour is not properly monitored to see if they are doing the job correctly.
My neighbour who himself is a contractor recently built a new house for himself. One fine day, a ceiling fan fell down, fortunately, no one was hurt. He called the electrician and gave him a piece of his mind. The bolt that holds the ceiling fan to ceiling uses a cotter pin. If someone forgets to put that cotter pin in place the nut will eventually unscrew itself and the fan could fall down and kill someone. These are very little things, but they can lead to big problems.
Without proper supervision, labour screws up all the time. Hey its not their house, all they care about is their daily wage. In the west they have proper standards and inspections to ensure that standards are being followed. I wonder when we will have something similar in Pakistan.