There are times that I do ask for a "finders/bird dog fee" if a buyer of mine buys a property that I've sent to them that I don't have under contract.

Thanks @Russell Brazil, I just sent Colin a message!

But recently I have sent them notification that since the banking issue was fixed they would need to start paying before the fifth or be penalized. 

His brother in law lived there before he was sent to the big house for a few months stay.

I don't mind using them after I've sent six letters over half a year. 

I'm assuming they sent over an addendum to the contract, these documents are always extremely seller friendly, and pretty much say the bank can do what it wants and has no liability for anything. 

I just sent you a message. 

I've sent mail to a similar list with minimal results and was wondering if door knocking would work better.

But it was only sent to agent (perhaps to keep things concealed?)

A question to ask the Seller (not the broker who sent you this offering wanting 3%) is, what lien position is the asset in?