I have taken on a new client who is already signed up for MTD vat. I sent the authorosation link as per the guidance for my ASA. The client has two Govt gateways, one for CIS and one for SA. Neither of these worked for them to be able to access and grant the authorisation.
Whats the best/easiest way now for client to authorise me as I am confused abiout how they can now do this?