Changing details where is FICA?

I received a message from Homechoice that I changed my contact details on Saturday, next thing on Monday I get a message from my Bank that I need to approve a debit order mandate. I called them and I was told the details I’m giving them are incorrect but my ID and name are correct, I was told they will block my account and not dispatch any goods. I’m hoping they keep to their word. How did they verify the change of address without my proof of address? What are their AML and FICA rules as we all need to comply? Are they not an accountable institution?