;If you have a written agreement that spells this out, and the realtor is in breach of this agreement, you can sue for breach of contract. You can ask the court for specific performance, which is a request to require the breaching party to fulfill his part of the agreement - in this case, it would be to require the realtor to pay the HOA dues.
Also, you can seek other damages, like attorneys fees.
Lawyer (JD)
Litigation Attorney practicing in multiple State and Federal Courts, Arbitrations and Mediations