Not to defend bad service, but the mail-order business is tough. The internet has changed everything and profit is an increasingly difficult thing to attain with so much competition.
If the manufacturer sells you (the retailer), for example, a pallet of chains where each one is labeled "144 link", you can only assume that they are what they are and send them out. Maybe check one or two to be sure. To expect the retailer to count every chain is just not reasonable.
Backordered items are not something we do, but I can understand the need to do it. We won't sell anything that is not currently available. All industries don't work that way though, and a customer should be notified immediately if they ordered an item that can't be shipped when promised.
The shipping thing is another major problem, we stopped using UPS because they would break so many parts that it became a losing proposition to use them. Customers would be furious with us, and blame US, and then not use us again because of UPS's mistake. That's really bad for business but to top it off, UPS would ALWAYS come up with some BS excuse that they were not at fault for running over that taillight package with their forklift. UPS has grown alot since the internet boom, but their service has suffered greatly. Needless to say, we use them as little as possible.
Bottom line in my opinion, from someone in the internet auto parts business, is that you should buy it locally IF you feel that the local shop will do a better job of getting the right part to you at the correct time. Many local shops will give you the same problems though, wrong part or they can't get it or whatever. Sales taxes will be more locally but the shipping times and cost should be less. Stick with the joint that was good to you I guess...