How do you rectify the de-bond tiles?

To rectify de-bond tiles, first, carefully remove the loose tiles using a chisel or a putty knife, ensuring not to damage surrounding tiles. Clean the substrate and the back of the tiles to remove old adhesive. Apply a suitable tile adhesive evenly on the substrate and the back of the tiles, then reposition the tiles, pressing firmly to ensure a strong bond. Finally, allow the adhesive to cure as per the manufacturer's instructions before grouting the joints.