Wax remover and wax sticks to scrape really. It comes out of carpet unnoticed but I have clothes that it will never come out of properly. Just looks greasy and are still a little sticky tens of washes later. You’d be better off reupholstering the seat and then using a plastic sheet over them when working.
I’d scrape as much off as possible. Perhaps pour some wax remover into the fabric. Soak it up with lots of kitchen roll then stick a seat cover over it if it still is sticky or looks horrid.
It happened to me aswell! I used a hair dryer to melt the wax and wipe off as much as I can then reheated the area with hair dryer and used some white spirit to get the residue of wax out! It's headache and it's gonna take you couple of hours but I think it's worth it!