I too had the same issue with the clunk. Of course the dealership could not verify, they like this so they can deny its real. I thought it might be the tow bars in the stowage area in the back, but not....Many other issues were denied as unverified but after other attempts they are now now confirmed. I started documenting with photos which helped as well.
As for customer care, the only proper way to address them is through a certified letter. I got into this loop and I am trying to re-start the process on a traceable path. They are careful to not officially respond so as to not start any clock. If you fill out a form on line, the record disappears. They do reply but give you extended hope not support. The certified letter requires them to officially respond in 40 days, else why would they? Personally I would not use the BBB Autoline as it is sponsored by the manufacturers, its third party not state admin, and they do not have to follow lemon law only consider it a guideline. If they can mediate that is OK, but likely its a waste of time. They rule 56% in favor of manufactures when used as arbitration,and their ruling is then used against you in courts as evidence. I tried them and they just claim the manufacturer has not responded there is nothing they can do. WOW what a help.
BTW...mine is out of service now for 57 days out of 100 and they still refuse to repurchase or even officially respond. It remains in the shop now for the brake squeal issue which they verified but Jaguar has denied as out of warranty with only 1200 miles most of which was returning to the dealership for repair. Others have commented about the same issues with a grinding noise or squeal. I have had by far the full gambit of issues including the clunk, but most importantly the death in road, failed charging cable, failed hood latch and failed repair, and rear sensors along with many others....rough ride? did I mention how crappy the ride is on our roads? I have full air suspension, but my Jeep with a similar set up is soooooo smooooth.
I know now the law is on my side and I just need to be patient. I really have a very problematic vehicle since day one. First clue was trying to get it started on day one the dealer even had a problem getting it to boot.