If you are getting DE in the pool, you have eihter a improperly installed set of grids or there is a small hole in one or more of them.

I went through the same thing late last year.

Since I'm a true believer in "If you want it done right, do it yourself", I pulled the filter apart and cleaned each grid. Then I went over each and every one of them spending almost 15-20 minutes on each one. I found one small hole near the manifold attachment on one of the grids, and I mean less than 1/2" stiching was coming apart and was causing a major issue for me.

If you don't want to mess with it, I would at least look into getting a new pool service. Sounds like the last guy wasn't very thorough