+1 on what Dave said.
Far too many people stick by the vendors with self-imposed inventory management challenges, and then pass (lack of) availability blame to the product manufactures.
29/40-120 cases have been readily available from multiple sources for some time. Here is one:
https://wildmanrocketry.com/collections/hobby-line
If your current source doesn't have product X in stock, but other vendors do, cancel the order from your current source, and draw some conclusions.
If your current source is refusing to cancel your order and refund the money they took from you 9 months ago, definitely draw some serious conclusions. And post vendor's name publicly, so that we can all avoid him.
YMMV,
a