Mold Issue

I have a part I’m sending out for molding and the vendor keeps telling me “there still have many striation was still 0.1 mm only”. There’s a bit of a language barrier and we’re working through an intermediary. So I’m not entirely clear what the issue is.
Anyone with more molding experience have and suggestions? Here’s the section of the file that’s giving them trouble I’ve been exporting as an STP.

Scale.3dm (12.9 MB)

In some areas the sweep section is not perpendicular to the two rails, making a surface that folds over itself a bit in areas such as this one:

Hi okeating.
Hope this can help.