My mother had two salesman sell her some windows for way more than she had to spend and actually needed. I did not find out until after the 3 day federal law for cancellation. The company rep was very rude to me and told me that older people do not like family helping on these decisions. I told him I think that is what the company wants. Is there any law that requires a co-signature of a witness if the buyer is over a specific age. My mother has memory loss and did not even remember everything she bought.
Unfortunately, there are scumbag companies that target elderly people. They use scare tactics or special "deals" to lure them in. These are usually home improvement and medical services companies. "No Solicitation" signs will keep them away from the front door in most cases. I wish there was a way to put a scumbag filter on the phone. The Do Not Call list hasn't worked at all.
One thing you can tell the company is there is no money to pay them. Maybe that will make them cease and desist. It would be nice not to have to pay a lawyer, especially if the contract is not over $5K.
What needs to be done is to find a good way to keep Mom and/or Dad from answering the door when it is someone they don't know. For my parents, I have a certain series of doorbell rings so they know it is me or my sig other at the door. I know this probably wouldn't work for all elders.
For myself, I won't answer the door unless I first look to see if there is a car in the driveway.