Unfortunately, it’s not unusual for banks to refuse to honor durable powers of attorney for one reason or another. In terms of the timeshares, I’m surprised that they need more than one original since timeshare ownership is usually not recorded like real estate. I’d push back on this.
They may be able to see the original and return it to you after making a copy or they may accept a copy certified to be true by a notary or a lawyer. I’d run all of these possible solutions by them.
If they won’t work, you may need to go to court to be appointed guardian or conservator for your mother. For more information on guardianships, check out this series of articles.