Walmart/Hyperwallet Account Hacked?

To preface, I am but a lone employee for my employer which is a large 3rd party seller across Amazon & Walmart. We've been on Walmart for about 2 years now and my boss has always used Payoneer to receive the funds from our account.

Recently, an unknown person created a Hyperwallet account under my name/identity, immediately changed the phone number & email associated to it and somehow also gained access to our Walmart account where they redirected our funds to their own financial service using "my new" Hyperwallet account.

So far I've reported the issue as identity theft to the FBI and contacted Hyperwallet where I provided my ID in order for them to freeze the account, which they did. However they refuse to assist any further and request us to continue the correspondence with Walmart. As we all know, Walmart's seller support is an absolute catastrophe and they've done absolutely nothing for us. They claim we have to log into Hyperwallet and unlink it first, but obviously that's not possible!

We're preparing to have attorney's get involved as well but we're at a loss of nearly $20,000 due to this. Has anyone out there had to deal with Walmart in this way before?