Best bet is to wet vac them mate with a decent shampoo. This will bring the seats back to an "as new" condition and get rid of the smell. If you dont know anyone with a vac you can borrow/rent get the ag interior shampoo and a small brush and really work it into the seat. Also try it on your carpets as the smell may be coming from elsewhere. good tip if you like the smell, is to get a tumble dryer sheet (bounce) and leave it under your seat on a hot day
I use this all the time http://www.vertar.com/car-care-exterior/wax-polish/zymol-royale-glaze/
Bargain!!