Help! tiles loose and lifting

[t5_nel]

Dave thanks again you have reassured me that there is a way forward.

Out of interest what depth did you plug to and what size screws, what plugs? I am guessing you want say 20mm in the concrete and I agree about using the zinc coated screws.

I am tempted to DIY this as I can prob get the help of a couple of others for a day.

I guess the process is
1 mark where the holes are on the board
2 put board in position
3 drill ply with wood bit
4 mark holes on concrete
5 move ply and drill concrete with masonry bit
6 plug and screw

then repeat 3000 times...