I am not sure what you are asking. I believe you are saying, "you put an offer on a property, and do not have representation." The "Agent" in question is working on the behalf and better interest of the seller, and you want someone to do the same for you. This is what I am assuming you mean.
If this is the scenario, all you have to do is find an Agent (of your choice) to work in your best interest, which includes negotiating the offer, aiding in property inspections, appraisals, etc. Of course you could just take the "Agent" the managing broker assigns to you. However, I would advise working with someone of your choice. Ask friends & family for recommendations. And PLEASE, do not avoid getting representation because you think it will cost you an arm and a leg. Typically, the seller pays most, if not ALL of the "Agent/Brokers Fee."
In my opinion, get an Agent that will represent your best interests, and someone that you are comfortable with.
I hope this answered your question. Should you have any further questions, please feel free to contact me by the ways below.
Wishing you the best of luck,
De Vonte Williamson
Licensed Real Estate Salesperson
Serving Long Island & Queens
Coldwell Banker Residential
"I Stand Behind Getting You Results!"