Seller back out of contract

[Cheryl Marks]

I Recently had a broker contact me to sell my property.

I agreed, signed the contract. When reviewing the Hud closing statement, I have a $22,000. Brokers fee. I called the broker and asked why? They said you agreed on this but it was never discussed or agreed. On brokers fee it says broker agree to pay other broker 4%. My concern and question is I'm the seller I'm not broker. 

The broker called me I didn't hire him. 

Please let me know my option to back out if possible. 

Sincerely, 

Cheryl Marks