How to appeal a rejected partner profile in the verification process

JillArmour After many, many months, I have finally been verified. In case it helps anyone else, here's what I've discovered:

1. Partner Center does NOT support Sole Traders, if you want your 'Trading As' name to be used as the publisher name. This is because (a) when registering as a 'Developer', there is only a entry box for the 'Publisher Name', which the verification team use for your legal verification - so that has to be the Legal Entity name (your name) and means your name gets used as the Publisher Name in AppSource / Commercial Marketplace; and (b) when linking your MPNID to an Azure application for login consent, the consent prompt shows your legal entity (name) rather than your trading name.  I ultimately gave up, registered a Limited Company and reapplied through that.
2. The first line of support - who respond to the 'Fix it now' uploads - are not allowed to engage in any conversation. They are only allowed to respond with the boiler-plate text we've all seen, which is rarely accurate. They are not allowed to use any discretion. As such, they're entirely useless if you have anything slightly out of the ordinary. In such cases, you need to raise a support ticket by clicking on the ? sign.
3. The Partner Center people on Twitter / X are similarly useless. They're all very nice, but just forward your queries to the first line of support, then ignore any requests for updates.
4. The second line of support - who respond to the support tickets - are not allowed to engage in any conversation. They are only allowed to respond with the boiler-plate text we've all seen, which is rarely accurate. They are not allowed to use any discretion. As such, they're entirely useless if you have anything slightly out of the ordinary. In such cases, you need to repeatedly reply with a request to escalate your case to the third line. You can also raise a support ticket on any other non-verification topic, arrange a conversation with the support specialist and ask them to escalate to the third line of support.
5. The third line of support are not allowed to engage in any verbal conversation. They can respond by email to explain the problem - to tell you what information is being missed  - but they're not allowed to tell you how to get past the blockage. They are not allowed to use any discretion. But they can trigger a 'Verified Credentials' process that might help you get through the "Who are you?" step.
6. The people who validate the domain registration details do not understand that '/' means 'or', so they *require* you to provide a "Domain registration invoice" with the name and address matching Partner Center, stating the registration period and who the domain is registered to. They don't seem to care who the invoice is from, nor for how much. In my case, I owned my domain but bought it under a different name. In desperation I invoiced myself for $0.01, uploaded that and got past the 'Domain verification' step. When switching to a Limited Company, I similarly invoiced my company for the domain registration, which was also accepted.
7. If you can, register for the "ISV Success" program. You need to tick that you're selling B2B and already have some products in other marketplaces, but they DO seem to be able to escalate to people who can actually use some discretion to verify your account.