I know little of the history and most of this is wiki regurgitation, although some is also local lore. That radio show was nationally broadcast and maybe was Elvis' first radio spot. He allegedly signed a 1-year contract to perform every weekend. One of the show's sponsors was a local donut shop (still here today, still great) and apparently not only did he love the donuts (he loved all food, it seems) but also
wrote a jingle for them. I've never heard it though.
I believe that location still stands, but they've added a "hot Hot HOT" sign that used to be lit when the donuts were fresh. It has reduced hours now if it's open at all.
*Just learned that Southern Maid has an Auckland franchise... (is there a mind blown emoji?)