What I would do?
Start looking for new seats from a salvage yard, Internet, or ebay.
or
Take them to my local automobile upholstery shop and have them remove the hides for me. I would then deep clean the hides and the cushioning. Then have the hides reinstalled professionally.
I have installed some armrests hides and MB Tex in some older Benzes, and thats not fun. Removing hides from the cushioning require specific tools and experience.
Not for me !!!
Either way will not be cheap.