Consumers who believe they may be due a refund from the Bally health club chain, which operates Holiday Health Spas in Maryland, must call the Federal Trade Commission hot line in Washington before the close of business today.

The deadline applies to Bally customers who have not filed written complaints and who think they may be due refunds because Bally charged their credit cards or debited their bank accounts without authorization. They also may be entitled to refunds if Bally used harassment or deception to collect consumer debts or failed to give prorated refunds when memberships were canceled.

The FTC number is (202) 326-3341.

The Maryland Consumer Protection Division said last week that the number has been very busy, but that the only way a customer can preserve rights under an FTC agreement with Bally is to get through by the close of business today.