What you have described here is a situation where the owner breached yet you want to sue the agent. On what basis? To collect money from someone, you must be able to show how/why that person owes you the money.
Before you file a complaint that potentially causes you to lose your right to recover, you should consult with an attorney regarding how to best proceed.
I hope this information helps answer your question(s).
~ Kem Eyo
The above answer is a general explanation of legal rights and procedures. It does not constitute legal advice. Nor does it establish an attorney-client relationship between the individual posting the question and the attorney providing the answer.
Depending in your contract, the entity or person holding the earnest money is in a fiduciary capacity and cannot release the funds without a fully executed termination and release statement. If one part refuses to sign, there is a dispute and the holder of the funds cannot pick who gets it. The holder of the earnest money can interplead the earnest money into court and each party can make a claim to the court. Unfortunately, with the amount being small, most of it may go to court costs and perhaps attorney fees.