Karl Hockless
Hi there Suhail. From my experience, grout starts to crack and break up when the tiles next to it are loose. You have mentioned in your post that some of the wall tiles and floor tiles are loose. This, therefore I would suggest is the root cause of your problem. No amount of re-grouting will correct this. SAFETY! If tiles are loose I would urge you to get this sorted straight away. Also keep any children out of the room. Can you imagine what a tile falling off the wall and hitting a child on the head may do? It sounds to me like the whole lot need to come off and be re-done. I would: a) Get the original tiler back to inspect the job. b) Look at getting an independent tiler round for a second opinion c) Find out what adhesive was used and speak to their technical people. You must also find out what primer was used. If it was PVA this might be part if the problem as this is not recognised as a correct tile adhesive primer although lots of people still use it. I hope this helps to point you n the right direction, Karl