Internet banking theft

I have been having money taken from my account every month. The reference on my statement was 2.99 Amazon video*M. I went to the bank and they said I could delete a debit order. The checked and could not find a debit order. Eventually they suggested I cancel my card and order a new one which I did this week. Today I recieved an e mail from Amazon Prime Video stating that I need up update my banking details so that they could process my membership fee. I tried to reply that I had never signed up for this or given them my back details and to ask for a refund but the e mail address was no-reply. I went to their website to try and find contact details, but there were no contact details available. Any suggestions as to how I can follow up with them?