Need help with Apple education store purchase

A few days ago, I ordered iPad Pro 11 inch 128gb for in-store pickup through Apple Education Store online. I had to change the pick up time, so I cancelled the order and placed a new order with a different pickup time (which seems to be the only way to do so). After that, I was having a second thought about the storage size, so I cancelled my order again to go with a bigger storage option. However, when I tried to check out, I get this error message that my order cannot be processed. The error message says "You have exceeded the product quantity limit for an item in your bag. As a result, we are unable to process your order."

It looks like the Apple website somehow thinks that I purchased two iPads already, which is the quantity limit per year for education store. I did order iPads twice but I cancelled both of them, so I should be able to place another order. I reached out to Apple representatives three times already, and they have not been able to help me; I even asked to connect with someone who can help me with this, and they said they can't, which is very frustrating. I could probably check out using a different email, but I have gift card points on my account that I want to use for this purchase.

I'm sorry if this is not the place to ask this kind of question, but I didn't know where else to ask since Apple customer support has not been helpful. Please let me know if there's any way to fix this order issue. Thank you.