thanks for your comments.
I'm not sure how thick the plywood was, but it was thin, I'd say it was about 0.75cm thick. I will include a photo of this in my album for you to see.
I'll upload some photos of the work whilst it was being carried out. Please can you take a look and thanks for your advice, I'm grateful.
you will notice from one of the photos there is the adhesive all over the floor before tiles went down, however when the builder came back a couple of months after the work was done and lifted a few of the wobbly tiles, I noticed there was no
cement type grout/adhesive underneath and he re-stuck the tiles with adhesive on the
tile, not on the ground. Unfortunately he only looked at 2 times and both are wobbly again (and more).
Now he is unresponsive, avoids my calls, texts etc and just seems to be dragging everything. I would be grateful of any advice form you as to the best way forward. What can I do? What shall I ask him to do to rectify the problem?
Thanks.