Why do I need to re-authorise banking connection two weeks after this was done?

The web application tells me that I need to re-authorise bank accounts (with Lloyds Bank) and when I attempt this, it FAILS, telling me to try again in a few hours. This is the second attempt - last night it did the same thing. Guess what - NO RESPONSE yet. By the way, I had already authorised the accounts TWO WEEKS ago and now the prompt has re-appeared. WHY?