New Funk Firm Achromat Warped

Music Direct is sending me a replacement mat. They were very accommodating.

Hi! 
Was the replacement mat ok?
Just asking cos I went through 3 and they were all warped (5mm thickness ones). However I flattened the last one a bit and have been using it as it really helps in tightening up the bass on my thorens. However the warp when combined with slightly warped records can become audible . I have also measured a negative effect with adjust+ software. The warp worsens speed variations quite considerably. So my problem is that  I really like the bass and added clarity the mat gives but the warp is becoming annoying. Are there any other mats I could try that are not as expensive but yield similar results?

The replacement mat was also warped. Music Direct accepted the second return and we gave up. I now use a Herbies Mat as a did before on my Rega P3-24.

Maybe the Vinyl Flat LP product would cure the mat's warp?

The warps must have something to do with the newer mats?  I have (2) of the 3mm and (2) of the 5mm, all of which are perfectly flat.  I bought these years ago and have never had a problem.