Report it again and insist they look at it. My car is at the SC now after two complaints. It helps to have them test drive it with you.
For what it's worth. I had a 3/2015 85D that had this problem and the seat was replaced under warranty in 2017, which solved the rocking motion. I sold that and bought a 12/2014 P85D that also had this problem, and it was replaced under warranty in 2018 which also solved the problem. Frankly, I don't expect much from Tesla anymore. My plan for out of warranty repair, when needed again, was to buy a used seat off eBay (which will likely also have the rocking problem) and do the Huck Bom replacement myself maintaining as high tolerances as possible, perhaps having some custom bushings machined to distribute the load better. It is still limited by the sheet metal of the seat frame.
Just as an update, Tesla ordered this part: US - MODEL S - LEFT-HAND DRIVE - LEFT HAND - FRONT SEAT CUSHION - NEXT-GEN - GRAY - MEMORY - SEALED HARNESS Part #: 1056258-04-B I'll have to wait and see if this solves the problem. Also not sure when I'll get the car back.
i have never had my seat loose or any issues with it, 2014 P85D. I suggest you pull the seat out and inspect the threads of the bolts and the threads of the spot they crew into. Likely one or both are stripped. If its the bolts just buy new ones at home depot if it's the nuts on the car then either try and replace, which probably isn't an option, so just go to autozone and get a helicoil for the proper thread pitch and install them and reassemble the seat and call it a day. If the threads are all good maybe the bolts were just loose put them back together with some blue loctite and see if that keeps it all snugged down. If all the mounts are good then move higher to the movement assembly and inspect it for lose/worn spots and repair as necessary.
That all sounds sensible and exactly what I expected the remedy to be, but sadly I think it is more complex than that. According to Tesla's technical bulletin it is caused by a problem with "the forward inboard Huck BOM fastener and pivot bushing (nearest to the center console) used on the front lift links. See post #10 above for a link to the Bulletin and post #13 above for my experience when I asked Tesla to carry out the repair. Needless to say my seat still rocks and I will just have to live with it. I'm not paying £1,000 for 'new' (old) seats with no guarantee the condition won't return. Elon Musk nearly got it right in his interview with Sandy Munro - "Seats like a rocking stone toadstool" would have covered it.
I purchased a used 2015 Model S 90D in 2019 and noticed the issue. The first time I went to the SC they said that they didn't notice any movement so they torqued seat bolts. I took it in again this past week and they performed the following under warranty: Concern: Seats - customer states: Driver’s seat is wobbly. Moves when car is in motion and while stationary. I had made an appointment before but the appointment disappeared? I believe this should be covered under warranty. Verified customer concern.Diagnosed and Installed Driver's Seat Assembly. Verified Proper Operation. Correction: General Diagnosis Correction: Seat Assembly - Driver's (Remove & Install) Parts Replaced or Added Part Quantity MS SEAT HRN PATCH MEMORY-SEAL TO UNSEAL (1139366-00-A) 1.0 EU-APAC-ASY-FS N GEN BLK LHD LH CUSH(1056287- 02-B) 1.0. I don't know what they actually did (don't know what these parts are) but this was their response and I'm going to pick up the car today.
looks like they replaced one seat cushion and needed a wiring adapter to match your cars wiring. Hope that fixed it. Seems unlikely to fix a seat frame with a worn pivot.
After picking up the car I asked a service rep to explain what parts were used and was advised that they replaced the seat. The seat is no longer moving and seems to be fixed. The first time they torqued the seat there was still some very minor movement but now there is none.
I got the bottom seat replaced and I do not notice the rocking.i think I posted the part number in a previous post.