Maryland Code, Commercial Law § 14-2505

(a) If a seller violates any provision of this subtitle, the buyer may cancel the sale by notifying the seller, in any manner and by any means, of the buyer's intention to cancel.

(b) If a seller fails to refund all payments in the time required, after the purchase complies with the requirements of the notice of cancellation a purchaser is entitled to payment of an additional 1 percent for each month or part of a month that the refund is not paid.