It's a DIY job.......the op has been doing the job himself...
Discuss Deflection issue with No More Ply down in the DIY Tiling Forum area at TilersForums.com.
Used NMP once, you need more glue than they advise...I'll stick with Hardie.
Reply to Deflection issue with No More Ply down in the DIY Tiling Forum area at TilersForums.com