How to handle repeat customer making multiple orders one after another

Amazon won’t allow me to use the same tracking number on multiple orders – it returns an error. And, yet, I have a repeat customer who places up to 12 separate orders one right after another. I have to ship them all separately. The customer is way overpaying for postage and I’m overpaying on fees. We’re also wasting time and packaging.

You can’t reach out to customers directly without risking your account. So, I can’t just email them and tell them this.

What do you do. I cringe when I see a while line of orders from the same customer. It’s such a waste of time and money for both of us.