So far as one plumber. Well, he is the plumber/ceramic tile/ handyman --he is commented on under them all, and none too favorable. Would like to make my comment that this is the plumber from hell, but, I will be nice. I will also, be honest.
Now, why do you call him a "plumber"? He is a handyman, clear and simple, regardless of any licenses he has.
I have had all kinds of "referral" companies call me, and they all promise to increase my revenue from their customers. I have yet to find any that do so, and since they want a fee, either you raise your price to those customers or accept a smaller profit margin. In addition, a lot of customers think that a service, like AL, is a discount site and you should be lowering your price or giving a "rebate".