I haven't turned on this function so why am I receiving authentication codes over and over? Started today. How can I turn this off when it hasn't been turned on?

I've had two bidders (three sales) disappear off the face of the earth so I applied and received an immediate refund for the first sale (closed 10 days ago) and then for the next two (closed 3 days ago). These last two weren't immediate refunds so I presume Trade Me has emailed the bidders a reminder. Do I have to wait three days for the bidders to respond (or not) to Trade Me before relisting?  I have emailed each bidder twice already and the reasons I'm moving to refund and relist quickly is because they both have a history of non-completion and the items are in a hot category that is qui...