Worst warranty no communication

Done a claim on behalf of a client and initially, the warranty relayed to client that payment will be made directly to us. They sent authorization with no invoicing details, I called to ask them for their invoicing details, I then sent them the invoice, but no payment was made and no communication was made that they needed any documents. I then called again, and they told me they needed documents so that they can add us to their system. I emailed them all the documents, and I even got an automated response email to say email was received.

When I called them after a week. they told me they didn't receive the email. They don't respond to emails. The client has his car for over 3 weeks now and we still never recieve payment and they tell me we must still wait 72 hours.