Amazon Relay-Invoicing/factoring

Does anyone know how to add a factor company to amazon relay? been trying to do it after the set up, so i am already set up but all i can do it change the bank info. does anyone else have experience with this?
or maybe does someone know how to find out about fuel advances?
would love a contact number other than their support ticket system because 3 tickets into it and no response from them

 

I have all that set up, did it personally, read through all the FAQs, talked to our factor company about it as well. I guess that's a big question in the factor community on how that all works.
I am told by the boss of our company that he wants to run everything with our factor, so I am kind of stuck, unless I can find someone explain how to get Amazon to work with the factor and get an assignment done with them. I have sent in support tickets, but absolutely no response