Sorry to hear about the difficulty you are having...
Sounds like their customer service is seriously lacking, but hopefully the product is solid once you can put it together. I was thinking of ordering the aerator from Gempler's as I hear they are an excellent company to deal with. Any reason that you didn't take the issue up with the shipper? Were you around to accept the package?
I ordered from Gempler's, even though there were some slightly cheaper places to buy from, thinking they would give me better service and support. No I was not home when it was delivered. UPS originally used the weather as an excuse for the late delivery. When I called them about the tracking status, they said they had to tape it up before delivering. Really, everyone has failed me: Feldmann, Gempler's, and UPS.
As I said the girls at both Gemplers and Feldmann were polite and tried to help. But, I think that this is a fundamental failure of their systems and lack of emphasis on accuracy and timeliness at making a sale right; plus they are ignorant about the products they represent. If the ladies knew what they were selling and had access to inventories, say via computer of all things (imagine that), they could have done better, even ordered and shipped the hardware kit in real time.
As for UPS, they clearly manhandled the shipment. I find they are the worst of the carriers. Express mail seems to do best. I don't know why more businesses don't use USPS. For these kinds of items, they are just as fast. And FedEx is better too, but this may have been too heavy for FedEx. Nonetheless Feldmann should have designed a more robust package for something so heavy. The weight/thickness of the cardboard is marginal. And had Feldmann packaged the hardware better, say in a sealed bag, it probably would have stayed with the shipment. The box contained an empty, unstapled, unsealed plastic bag and had holes large enough for individual hardware to escape. Once the hardware was out of the bag, with the holes, it clearly was going to get lost. It was clear the bag was never secured shut (no signs of staples, no tearing of plastic, no evidence of thermal seals).