Accounting and Compliance question?

I work for an ad agency and we hire talent and freelancers quite often. Lately it have come to my attention that we have a rather strange accounting practice when it comes to paying off our vendors and freelancers. The agreements we make with these companies and individuals state that we will be the ones paying them not our clients which we represent; however it seems to be corporate strategy and procedure not to pay off our vendors until our client pays us for the job we did for them. The problem comes in when we are invoiced by our vendor with in a couple of days after we use their services and often a job isn't completed for months sometime and everything is packaged together for billing when it comes to our clients. Our vendors call us after 30 days asking were their money is? We are told to stall them or ignore their demands citing that we won't pay them until we get paid. I'm not an expert but this can't be legal or legitimate accounting practices? Which Laws are we violating