If you have a problem with Amazon, for example deactivation, you can request independent mediation to resolve the issue either way. You normally have to pay for this service.
The message clarifies some details.
The case will be questioned by a team that treats problems subjectively, not objectively, and even looks over your problem, not like those from seller support or those from account health. If they don’t solve your problem, they will give you a code and you will register with CEDR where an external person (I think a lawyer) will analyze your situation. The whole thing costs between €500-€1000, but if you win the case, Amazon will pay all the costs. I don’t know if it’s also for the UK and US markets, but it’s definitely for the EU market. It’s a good thing and the response time is 10-15 days, but you do that after you’ve exhausted all resources with Seller support and those from Account Health.