I have to agree that I don't think the other company was trying to "steal" work from you. I agree with many of the others that have said that the other company was most likely trying to keep a high paying customer happy. They may have given your customer that $500 job or whatever as as a customer appretiation token for all the business that your customer does with their company. Unfortunetely things like this do happen some of the time. If it becomes regualr habit then, I would reconsider my business relationship. However I don't think that there was any maliciousness intended. The thing I have had and heard of being a problem is people stealing your yard signs.