I disassembled my wives 550i seat. The right bolster wasn't working. What I discover is a broken plastic mechanism that moves the right bolster. You can see it on the picture. The front part came out of the pocket and the back part I pulled out. Is it possible to purchase this part anywhere? If so does anyone know the part number?
If I was to pull it out and try to fix it, it won't last very long as I compared it to the left side and it broke at the point where plastic is no longer comes into contact with the pocket.

 

I called the dealership and the guy quoted $14 and $8 for 2 parts but recommended to come to check it out as he wasn't 100% sure. It had to be special ordered from Germany.
I looked in TIS manual and realized I will have to take the seat out and remove the leather. Also the manual states the motor with wires and sliding rails has to be replaced all at once. Instead I unhooked the leather on the right side to give some extra room to place the sliding plastic back into the pocket. It was long enough to barely show up on the other side of the pocket. I installed the broken piece and everything worked as expected. I looked around the house and found some epoxy, but it was generic one, not the one designed for plastic. So I went to hardware store and bought 5min epoxy(2 tubes) for plastic. I applied it to both sides and moved the bolster in and out to prevent the residual epoxy sticking to pocket walls. The cable puts a lot of pressure to hold the 2 broken parts together. I moved the bolsters half way, reprogrammed my wife's preset and told her don't adjust the bolsters until tomorrow.
I thought I will report back, perhaps this will be useful for someone in the future.
I may upload some pictures later on, but they are not that great.

 

good luck on the repair holding up!

 

Thank you. If anything I won't even order replacement parts, but instead I will reinforce it by glueing a piece of metal sheet.