Thanks for your patience and enquiry.
This is a very difficult situation because you are right, one really does not expect that things would become undone after three years.
A contractor does have an obligation to ensure that work is carried out and completed in a proper and workmanlike manner. Typically a workman is required to ensure that the renovation work is done with skill and care, using good quality materials.
The difficulty you will have though is that work such as these, as pointed out by the contractor does have a 12 months window where if a defect is found it would be up to the builder to repair. After this time, the builder would not be liable and even if you were to take the builder to court it would be difficult for you to show that the tiles have lifted due to the builders poor workmanship and not as a result of any other factor.
I know this is not ideally the news that you were looking for . I am however required to let you know your legal position as I understand it to be so that you are not misinformed.
Can I clarify anything for you? I hope I have answered your query in a way that is simple and easy to understand. If anything remains unclear, I will be more than happy to clarify it for you. In the meantime, thank you once again for using our services.