HLN Money Expert Clark Howard answers your questions every night on Evening Express. His email question of the week comes from Linda in Indiana.

"My mother is 90 years old and lives alone. She's in great health but her mind is fading a little, and she doesn't make very good decisions on her own. Is there any way I can stop charities, etc., from calling her and asking for money? She can't seem to stop herself from donating, and the scariest part, giving her credit card number over the phone, even though we've warned her repeatedly not to do this."

Clark has been through a similar situation with his own mom. He says resolving this will be messy and possibly painful.

If you have an elderly relative in this situation, you can't stop people from calling. So the first step is to take away their credit cards and checkbook. Next, obtain durable power of attorney, and durable power of attorney for health care. There are state-standard forms available online, or you can hire a lawyer to prepare the documents. If your relative is still considered mentally capable, he or she can sign and authorize them.

If you have siblings or other relatives who can help, get them involved.

Get more great advice from Clark on Evening Express, weeknights from 5 pm to 7 pm on HLN.