Unsuccessful Mandate

I have been trying to complete my Reporting Mandate and keep getting "Unsuccessful Mandate". This is extremely frustrating as I am relying on this income to pay my rent. Calling is a waste of time and emails are ignored. It is impossible to fix this issue and I will be evicted at the end of the month if this is not fixed. I have no idea how to resolve this as all the info I add is correct. Extremely stressed and frustrated with the service here.