Contractor unable to get rid of pet odor.

The house I bought had a strong pet odor, cat urine, and as part of the scope of work, I asked contractor to eliminate that odor, however house was repainted and work 99% complete, but odor came back. Contractor assured me smell would go away after house repainted, but that's not the case. Pet odor removal services cost between $8k to $10k. Any advice.