First, There is nowhere that MBkings occur pure. They are a phase of L.g.splendida. That is, in parts of L.g.splendidas range, there are also black ones. In some parts of the range, the percentage is fairly high. From someone who has caught the dang things(me) that, patterned juvinile occurs normally.
Its very much the same as Stripe and banded calkings found in the San Diego area. Or many of the other areas were two or more color phases occur, Medona, LAx etc. Those areas have normal cal kings and black types too.
Next, in most cases, breeders sell pure black babies for a higher price then their patterned siblings. So, did you pay a lower price for a patterned MBK and now are complaining about it? Tell the true. In otherwords, why did you hand over money for that snake at the show, if it was not all black then?
I am not trying to attack you or defend the breeder, but there is ALWAYS many sides to the story.
The truth is, some of those babies stay patterned and thats the risk you have to take. Thats why patterned babies are sold for less.
Common sense tells me, if you really wanted a pure black king, then you should have bought a pure black king, not one with pattern.
Not that this is the case here, but reptile shows for full up with misrepresented reptiles. Let the buyer beware. Cheers