The secret to deodourisation from any source is complete or as nearly complete as possible removal of the contaminant. Only by doing this can you have any hope of success. There are no magic formulas that you can just spray on. There are some really good products but you have to give them a fighting chance.
We guarantee odour removal for isurance companies. In extreme cases this entails removing parts of the structure and even subfloors.
For urine in carpets you need to treat both the face fibres, backing, underlay and floor. If its wool then the urine will have absorbed into the wool fibres so you have to soak and flush a number of times to get it back out. In bad areas such as nursing homes the concrete floor under the carpet may have absorbed a substantial amount. This will keep on giving off an odour as long as its untreated. Give it a good clean, treat it with urine treatment then sheet it over with damproof membrane before putting the carpet back down on it. This is a good part of this business and should be charged for over and above a general carpet clean.