Screw that guy. My advice work on you negotiation skills. Get those clients back and get more. Get out there and set yourself apart from what the others can do. 90% of this is plain simple physiology and the mentality of a customer thinking they're getting a great service for the price that they pay. Usually undercutting will win the stakes easily. BUT, you CAN and WILL get those customers back. Simply ask them what you did wrong and why the sudden change of heart besides the price. After that show them the great reviews you've gotten and how much better your service is even though it's more expensive. Assimilate them into getting into the mindset of "You pay what you get" and that way you can try to get them back. Don't worry man, this is the sport. The fittest of the pack survive. You've just been removed from the alphamale, time to regain your position again.
Hope that helps,
BA,