I would go back and reread the "non competitive" clause of the contract. If it is written like most, it will read that you cannot directly compete for your bosses business or take their current clients with you. Then I'd find an agency far enough away from them as to not break the original contract and negotiate a better deal with the new company than the one I had. Once secured, either return to my boss with the new offer and ask them to meet it or beat it, or if you hate them that much - just leave and go to the new company.