How to get charities to stop calling father in law with dementia?

I went through this. They were really good and called my mom almost daily. Sent her all over town to send money to them in Jamaica. She gave everything away. Every. Thing. Water had been cut off. Lights were cut off several times. They convinced her she won the lottery, they just needed $1500 to process it. Over and over and over. It was a mess to fix.
Ended up changing the incoming phone calls. If you weren’t on a pre-approved list, your phone calls don’t get to the house. There’s nothing but fake phone numbers calling but now they’re gone. I gave the doctors offices my cell number (those appointment reminders don’t usually come from the office number) and that’s how I keep up.
That’s the only way to stop the calls. I turn it off occasionally to see what happens. Within 15 minutes they start right back up again.
You’ve got to do it ASAP before you lose any more money.
Wishing you all the best!

I don't know if he lives alone or not. This is what I finally did with my husband who has Alzheimer's. i turned off the ringer on the house phones. He could call out but any incoming calls went to voicemail. He has a cell phone and odd as it can be, occasionally if he gets a phone call soliciting money, he is sure it is a scam. I also have blocked one relative from calling him on either phone.

Get a call blocking phone, At&t or vtech. These phones allow you to block most calls and allow only those numbers you program in the"allow"list to ring through. You can also allow certain businesses to ring through like a doctors office or pharmacy. This phone has made my mother's house very quiet. The phone only rings for family members and friends.

Do you have POA? I say this because you need to take control of his financial life pronto!

He no longer needs access to this VISA card, so I hope you can find a way to wrangle it away from him. Cut it up. Cancel it!