Hello and thank you for contacting us. This is Dwayne B. and I’m an expert here and looking forward to assisting you today. If at any point any of my answers aren’t clear please don’t hesitate to ask for clarification. Also, I can only answer the questions you specifically ask and based on the facts that you give so please be sure that you ask the questions you want to ask and provide all necessary facts.
At some point they could likely get a lien on the house but realistically there isn't much they can do with that lien since you have a reverse mortgage. They can't seize your social security payments or an account in which your social security payments are kept although they could seize any extra monies that go into that account from any other source.
They can't force you to sign the new papers. They can hold you to the contract and they are correct in that you had three days to change your mind but you can argue that since no work had started then the contract hadn't been completed yet.
Your best bet is to go to a local lawyer and let them examine your financial situation and make sure there isn't something there that we haven't discussed (such as other assets) and they can also write the company a letter to advise them that they are 1) not to proceed with the installation and 2) not to contact you. Most lawyer won't charge much, if anything, to send this letter for you.
In the meantime, there is nothing that says you have to allow them in your home.
To sum up, they likely can't collect any money from you even if they sue and get a judgment and because of this it makes them less likely to sue.