Take money from a company that stole from you

Peace be upon you. I dealt with a large company, and they were unfair in some of their dealings. They took more money than the contract stipulated, and I paid them money for services, but they didn't do it, which created for me many problems with my business. They didn't abide by all the terms of the contract. Since they are a large company with lawyers, I couldn't do anything but terminate the contract. They took about $7,000 from me in total. However, when they paied the final invoice, they made a mistake and overcharged me by $10,000. Should I inform them of the mistake? Or should I just ignore it since they didn't treat me honestly? The amout that they give my error is more that what i owe them, but if i signal that to them i will be forced to give back all the 10k May God bless you.