I've just cancelled both Citi and NAB. It wasn't until I got the NAB card that I realised that it was a Visa. (This was NOT a fault with NAB. Entirely my fault for overlooking where it was painly and often stated that the NAB would be a Visa.) Already having a couple of Visa cards, a minor reason for having the Citi card was because it was MasterCard.
Cancelling the Citi was easy. Emptied the account and rang them. After some explaining and verifying, the account was closed and will be cancelled completely in a couple of days. Seven minutes in total.
I went to a NAB branch to close the NAB account. Spoke to the "greeter" who asked me to take a seat and told me that someone would be with me shortly. Fifteen minutes later with not a thing happening - not even a "sorry to keep you waiting" - I gave up and left, pointing out that their sign along the lines of "We respect you, please respect us" was rubbish.
I tried doing a chat session through the NAB app, and after the initial toing-and-froing, had to wait for 1 hour 22 minutes until a person got to me. And they told me that they couldn't cancel the NAB account, implying that it could only be done in February, when the funds had been transferred over from the Citi account. I replied and said that both accounts were empty.
Another 20 minutes of silence, then someone from NAB's Citi Migration team came onto the chat and said they could close the NAB account. After giving me warnings about the benefits I would lose by closing the account, and yet another 20 minutes of silence, they did set the process in motion.
I've cut up the cards, and opened a BankWest (MasterCard) account.
[I've had a moan about it. I feel better now. <g>]