I've had an issue with my shower door, too. I don't know that your shower enclosure and mine are the same, but I did look at some pictures of a unit the same as yours and the enclosures are at least very similar, if not identical.
And the problem mine had was similar, too. The top of the door and the bottom of the door were not parallel to the frame; the bottom really dragged on the "sill" when opening or closing the door. My issue was repaired by the dealer under the warranty. The dealer told me that there was no adjustment and that the cure was to reset the entire enclosure framing. This the dealer did, and the problem was solved. The adjustment was about 1/2 inch along one wall; the dealer inserted an extra piece of aluminum square tubing in the area. The repair looks OK, and the door is now square in the frame and works properly.
There's lots of advice and information in forums... sometimes it is correct. For example, all of my posts are made by a political appointee who got the job as a reward for contributions to my diesel bill.
2011 Jayco 28.5RLS; 2008 Chevy Duramax; Pullrite Superglide Hitch