Partnership Agreement Dispute | client won't pay for completed work

Looking for advice on a legal issue. Here's what happened.

client won't pay for completed work. I've been dealing with this for about 4 weeks now and the situation isn't improving.

The contract was signed 6 months ago. I have a copy of the original agreement. The total amount in dispute is approximately $127,000.

Has anyone been through something similar? What worked for you?

I talked to a lawyer when this happened to me. Worth every penny.