I need to link my account with Apple Business Manager

I have called customer service and our retail store at least a dozen time. I talked with our business rep. and no one has a single clue what I'm talking about or tell me they can't help. I need to link Apple Business Manager to our AT&T account. Someone from customer service even told me that they can see info about it in their knowledge base but can't do anything. I've even contacted Apple support to see if maybe I've missed something on my end.

The directions from Apple Support were as follows:

If you purchased your devices from an Apple Authorized Reseller (which we did - AT&T), ask them for their reseller ID and provide them w/ your organization ID. 

There is literally NO ONE at AT&T that has any idea what I'm inquiring about when I ask. I have our organization ID # from Apple, I just need the reseller number and AT&T to link the accounts. Someone help. I'm almost at the point of cutting off all service with AT&T!