FICA DOCUMENTS EMAIL

I receive a so called final demand from FNB. They claim that these are important documents and I need to fill them and revert to them attaching also my ID document. The state that my account will be freezer in a few days. I wondered why do they just send an email with an issue which have such implications. I dont usually check emails. If I had not seen this email I was going to be suprized at the store trying to buy diapers for my child to learn that my account account is freeze. I not impressed with this. FNB could have at least SMSed me it cost R1,50 I would mind if they charge me for it in my bank charges. Due to this I believe FNB and degenerated to a mediocre bank I am leave it.