[Samsung Galaxy S8 Questions and Answers] FluxionFluff:
Oh noes, that's not good. D: Unless you got unlucky and they were in the middle of maintenance, that's pretty strange. Have you tried to contact them, either over the phone or in-store?

Hm, curious about that too. My best guess is that to cancel orders, as long as they haven't started to prep your order for shipping, you should be able to cancel it without too much difficulty. Most companies are like that. Otherwise, you have to return it after you get the items. With returns, I don't know how strict Samsung is, because I've seen all kinds of return policies -- from no returns besides exchanges, can only returned unopened ones within a certain time frame, to ones that say that if you're not happy, return it and you're fine.

You might be charged a restocking fee, might have to pay for shipping upfront OR it gets deducted from the original amount you spent on the purchase, minus shipping and handling. Before you buy ANYTHING from any site, it's ALWAYS good to look at their return policy, so you know what you can expect if you have to return. What I said is more general ordering and canceling orders, but at least it's a start, haha.

EDIT TO ADD: So, I did a quick check to Samsung's site, so we'll all know it for future ref. Here's what I found, copying directly from their FAQ:

TLDR: Basically, you need to contact them directly on the phone or over email to initiate a return/exchange. You MUST have an RMA # before sending items back within 14 days (for phones, 30 days for everything else) of receiving your order. Looks like you have to pay to ship stuff back. If you opened it, you're may be subject to a 15% restocking fee. See below for more details.

What is your return policy?

Except for certain phones purchased on Samsung.com, you have 30 days from the date we shipped your product to receive a refund. All returns must be authorized by Samsung prior to sending.

Returning a Phone:

To return or exchange defective or unopened phones, customers must (a) obtain an RMA number within 14 calendar days of the date the order was shipped to the delivery address specified on the order and (b) return the merchandise to Samsung Direct within the Return Period of 14 calendar days of the date the RMA number was issued by Samsung Direct.

How do I return or exchange a product?

To return or exchange by mail, please call us toll-free at 855-726-8721, seven days a week, 9 a.m.-9 p.m. EST to return or exchange your merchandise. For exchanges it will be necessary for us to process your exchange as a refund followed by a new order.

What should I do if I am dissatisfied with my purchase from Samsung.com?

Your satisfaction is of the utmost importance to us, and we do everything we can to ensure that your experience at Samsung.com makes your life a little easier. For your convenience, you may return or exchange merchandise you purchased online within 30 days of purchase. Please note that you may be charged a 15% Restocking Fee for non-defective returned items.

Please call us toll-free at 855-726-8721, seven days a week, 9 a.m.-9 p.m. EST to return or exchange your merchandise.

We apologize for any inconvenience this may have caused. We do everything we can to ensure that your experience at Samsung.com makes your life just a little easier, and will do everything we can to remedy the situation as soon as possible.