Getting rid of pee from a carpet

[Redberry34]

Anybody got tips on how to get rid of the smell of pee from a carpet. My ex let my wee one run about without his nappy on but didn't clean up an accident. Says he never realised, now my carpet is stinking and i have tried shampooing it and scrubing it but the odour is still there.
Any ideas?

If you've shampooed (RugDoctor?)it soaked through to the underlay/floorboards then you might need to replace the carpet. Sorry :(

Not sure where I got this but I think vinegar in water sprayed onto the area is supposed to work. I used to use it when DD was a baby as she threw up a lot and the smell of sick was vile.

Recently she wet herself and I used a steam mop directly on the area and let it steam over the area moving slowly and letting the steam works its way in and that seemed to work.

Also, vanish carpet spray is another one that is quite good, although it's obviously chemically.