Unable to submit VAT Return from Kashflow

I have tried to submit the VAT Return for Kilrot on Kashflow and it has Failed with an error saying I am not authorised to submit it on MTD. Nothing has changed on the system and I have checked that the login details have not changed accidentally or been corrupted. Can you suggest what the problem might be?

Hi Kilrot,
Please contact our Online services Helpdesk here:
Get help using VAT online services
So that we can look at resolving this issue for you.
Thank you.