I tried to make a tool to be able to squeeze front and rear locks in plastic retainers, but no luck - poor access -not enough slack to see or access anything. I used crowbar at the end, and it was not easy - around 10 mintues of struggle, a lot of sweat and cursing... Old retainers were then completely damaged (white parts fell down, needed long tweezers to remove them so they won't rattle inside body).
I bought new retainers (cost like EUR7 for pair), fitted them, but no longer the seat was perfectly tied - I guess these metal hooks for plastic clips of retainers sticking out of the seat get bend because of force generated through crowbar, and the seat got too much slack this time. After a few weeks I need to remove again the seat (I was replacing standard H7 lights for original xenon headlamps & adding levelling that required to create new wiring looms(I was not the lucky one, I didn't have these)), and this time straight I used crowbar, in 1 minute got seat out. I didn't buy new plastic retainers - seat is just placed and locked by the other brackets/hooks (2a-d on eLearn snapshots), I only wrapped with the tape 1b hooks, so they won't be scratching through metal under the seat. All is good I'd say, no noises so I've forgot about this until today seeing new post about rear seat removal.