Linking Amazon shipping and Royal mail C+D

Can anyone help??

I have been told by our royal mail account manager that we need to link our click and drop account to Amazon so that we can use Amazon’s buy shipping method but still use our prices we have from Royal Mail.

I have spoken to Amazon support but they seem to have no idea what I am going on about.

Does anyone know if there is a way this can be done?

Thank you in advance.