So then you just order another one? Unless you had some kind of hard deadline for when you needed the shower, you were in the same position as before you placed the first order.
It sounds like they handled this particular situation completely reasonably (modulo the least-effort job everyone does these days), and your expectations were off. If you're ordering stuff online, the table stakes include waiting and dealing with exceptions.
Inconsistent experience. I had bought other things with them that arrived in the expected deadline with no troubles. This is the kind of deal that I'm willing to make. I buy something from you, you tell me when you are going to delivery, i get the product.
Once there's delays and problems with the delivery (like giving my product to someone else) it makes me not to want to buy from you again; cause I'm not sure when I'll get my product or even if I'll get it.
But "inconsistent experience" basically applies to everywhere these days. I could complain about Amazon's delivery, just like I could complain about USPS, UPS, and Fedex - each doing their own different but still craptastic thing.
Gone are the days where individual employees went above and beyond to make sure every customer was taken care with the details making sense, because gone are the days where companies treated employees like humans rather than expendable cogs. I've had boxes of leaking oil paint left on my doorstep at 9PM - the package was able to be marked as delivered on the promised day, and therefore everything was right in their system.
Do I blame Home Depot (the vendor) for that, or Rustoleum (the actual shipper), or UPS (the delivery company)? All of them and none of them specifically - it's "nobody's fault". Instead I complained to Home Depot for a refund and 20% off the reship, cleaned up the mess myself, saved the remaining 3 gallons of paint that hadn't flowed out of the cans into a new bucket to use later, and didn't feel bad about getting that paint for free. That's the best I could make of the situation - screaming at the customer service drones wouldn't have gotten me a better outcome. That's life in the 2020's.
You can certainly eliminate the variability of delivery - go to a brick and mortar store with stock. But the same caveat emptor maxim applies. You'd still better inspect what you're buying, because otherwise there's a chance you'll get it home and it will be defective in some way and you'll have to return it and do the whole process over again.
As someone who used to only return things if there was a serious problem or if I earnestly changed my mind, this really bugged me at first. But now I've just accepted this is how things work. I'll even buy things on sale that I just might want, knowing I've got a month or three to actually decide (with my only cost being the work required to effect a return). Companies wanted this regime of no honor besides blindly their fully formalized procedures, and so I'll play my part.
It sounds like they handled this particular situation completely reasonably (modulo the least-effort job everyone does these days), and your expectations were off. If you're ordering stuff online, the table stakes include waiting and dealing with exceptions.