my 03 wrx driver seat cover comes apart all the time. It seems that the C shaped plastic strip doesn't want to hold the straight edge plastic piece on the other part of the seat cover. I've slid it back togeter a few times but as soon as get back into the car, it pops apart. Any ideas short of gluing/sewing together, as would like to bee ablee to pake apart periodically to clean it. Subaru doesn't know why and seeing it's out oof warranty the only suggestions they have is A - replace cover, B - rip seat out of car and have a better look, which the labour would almost cost the same as a new seat cover.

Take the cover off, take it to a professional and have a zipper fitted.