Are you asking ironically? Because it is obvious they would not tell you, assuming they are actually trying to start a business with bets, it is within their own interest you not getting access to the same books they have contacted, otherwise their services would not be necessary as a third party.  Actually, any betting agent with an good reputation already established would never allow you to know where they are getting the liquidity from and how the whole chain of bets is managed, it would be translated in puting their own business model in jeopardy. 

If you were a merchant, how would you react if some client came to you asking where you get your merchandise from at lower price? It is plain common sense.