I recently placed an order via the 3DR store, and was pretty disappointed with how it was handled.
One of the items was backordered, so I contacted customer service and asked for an estimated dispatch time. It was only a few days, so I was happy to wait. I had paid for express shipping, so I had expected the parts to arrive a couple of days after the 're-stock' date.
10 days after the 're-stock' date, my order was still on 'backorder', despite every part being instock. I emailed customer support, and within an hour my order had shipped, with an apology about the delay.
The order arrives, but one of the parts I had specifically requested was in the wrong configuration. Customer service told me that the requested part had gone out of stock, so they sent me this one to fill my order. If I wanted to change it, I had to pay to post it back (international postage, not cheap), and they wouldn't post me a replacement until they received it.
From my perspective, this indicates that there are some systematic problems with 3DR's service. Are orders that have components on backorder being set aside? When a component returns to stock, are backorders being prioritised? Why are incorrect parts knowingly being sent, without contacting buyers first? If 3DR admits that it is their mistake, why are they punishing their customer to rectify it?