Legal Question in Civil Litigation in Maryland

Generally, no. Private companies are free to change their rates at any time and do not need to retroactively apply discounts. If the company did not keep the terms of its contract with you or if they had false or deceptive advertisements, there may be some cause of action.

That being said, oftentimes if you bring this to a vendor's attention they may for goodwill honor pricing changes.

While I hope this general legal information helps, it does not substitute for legal advice on the specifics of your situation.