Greenlight policy change of banking derails

We took out a death benefit greenlight policy for my mother and I was paying for it. I changed baking details in May this year and have since struggled to change the banking details. Last month they told me that it has been forwarded to the relevant department and when can they rerun for August I said immediately. October debit still went off on the wrong bank account, today when I phoned they told me that my mother needs to complete a form to reinstate her policy due to non payment yet I have been asking them to change banking details.

Such poor service and no apologies for their mistakes and incompetence.