Bad service - debit taken before agreed date.

My debit order date is the 27th of each month yet A&G took the money today, 25th Jan. When I call and ask what is happening the consultant says the bank sent a debit check approval asking if they may debit my account earlier. I didn’t get any request and she confirms that I never approved it but regardless of whether I approve it or not Auto & Gen will continue to debit earlier. She also confirmed that my date is the 27th and no changes have been made. I have never missed a premium with them the whole time I’ve been their customer so I don’t understand why this happening. What is the point of having an agreement on the date if you are going to debit whenever you see fit? I’ve been with other insurers and this has never happened. I’m definitely cancelling my policy and moving over to another one. This has inconvenienced me immensely as I was supposed to travel this morning and I woke up to my money gone.