seats out, normal vac and then wet vac seats and carpet multiple times until the wet vac water doesn't look like Newcastle brown. let it dry then spray it all, including head lining with autoglym anti-stink spray. That's what I did to get rid of dog hairs/stench.
How big a job is it removing the seats ?
What with all the electronics etc and warning lights 🤔
Used to be a 5 min job in my old MK2
Certainly not a 5 minute job in the mk5, though not too bad. 4 bolts holding each seat. They are triple square heads, but can't remember the size. Possibly M10. You need to disconnect the battery before unplugging the seat wiring harness, otherwise you'll get the airbag warning light come on, on the instrument cluster.
After that, just remove seat. I find it's easiest to have the seat back wound all the way forward and have the head rest removed. The seats are surprisingly heavy.