Regarding non-residency certification....as it was not compulsory to do this in the past to open or run a bank account... I think the problem at the moment is that not all banks did this certification and had their own set practices and it is now difficult to determine if you specifically have a problem now.
One of my banks that I have had an account for many years did this and I re-sign a non-residency certification document every two years (which is the validity period of the document)....so that seems to be covered there....but one my other banks which I have been with less than the two years I dont remember signing anything specific, but then I signed a lot of documents on opening so it may have been one in there.
Best thing to do is check with your own bank(s).