Advice needed: Preventing my elderly grandmother from making excessive orders via landline

Hi everyone, I’m the caretaker for my elderly Japanese grandmother, and I’m struggling to manage her purchases. She often buys expensive items she doesn’t need and forgets that she even ordered them.

I’ve managed her online shopping by blocking certain sites on her computer and having her use only my Amazon account, which lets me cancel orders after she places them. While this has helped, she still makes large catalog orders, like through Co-op, by calling the numbers listed when I’m not around. She often ends up placing multiple orders at once and gets upset when the deliveries arrive, since she forgets she even ordered them.

Her landline is a Panasonic KX‑PZ620‑W with service from NTT. I assume it can block incoming calls, but I need a way to block outgoing calls to specific numbers if possible.

If anyone has any ideas, advice, or workarounds I’d really appreciate it.

by trashijordii