Amazon FBA Carrier Central did not process our appointment and our shipment is returning by carrier

Hi everyone,

Maybe you are facing this type of issue and I would appreciate it if you have any experience to share it with me.

We have requested the appointment from Amazon carrier central weblink that our shipment is on the way and we need to get the appointment and ISA number.
Unfortunately, they did not respond to our official request through the link, emails, and calls to FBA and once the carrier arrived at Amazon FBA, they rejected the driver (carrier). So after 24 hours our carrier is going to return our shipment.

We have done all the paper works and paid the customs clearance, tax and shipping cost and now our shipment is on the ground without delivering it.

Amazon seller support is a disaster as always and just we get a generic response from an uneducated support team.

Any suggestions, what we have to do? There is no hotline to call regarding this issue and they do not respond to emails.

Thank you!