Can a reverse mortgage company break a signed agreement?

I signed an agreement to make 24 tax reimbursement payments to a reverse mortgage company who paid my propet4y taxes for the first half of last year. I have made nine payments ON TIME and have fifteen payments to go. Recently I got a letter from them saying they are voiding the agreement and I need to pay the balance within 60 days - which I CANNOT DO! They claim that they have to obey HUD's new rules. There was NOcancellation clause in the agreement! I have already shot a letter off to HUD! Thoughts?

I need to say that the company is in reality a "collection" agency because it got "burned" in the housing bubble in "08!" They ARE NOT offering any more reverse mortgages.

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