So with the carpets having something that resembelled hard chewing gum in but far stickier and harder, didn't think anything was going to get it off. Freezing didn't work, carpet cleaners didn't.
So in the end I spot a wallpaper steamer with a small attatchment.
Grab a wet vac, get the steamer warming and spray liberal amounts of AG Interior Shampoo all over the footwell, especially on the stains. Then held the stripper on the carpet for a while. It got right in there and started foaming the shampoo like mad and then start moving the steamer about and used it to scrape the stains away. Quick wipe with a cloth and then another steam all over and a wet vac.
Stains gone!