Change of Debit Order Date

I wanted to change the debit order date from 31st to the 25th of every month. The bank account number is still the same and no personal details have changed. I sent an email to Assupol and the response from their customer service was that the request has been denied because of the following reasons. Completed debit order form

• Bank statement/proof of account

• Id copy of the premium payer I find this unnecessary because I'm not putting a claim. So, this gives me an idea that I'm going to be sent from pillar to post the day I want put in a claim.