What do you dislike about Next Day Flyers?
The customer service team is difficult to get a hold off, unresponsive, and dismissive. 
I submitted an order to receive it by a certain day, with a couple of days cushion to ensure the order would arrive in time. I requested a proof to make sure there were no issues with my design, expecting, as has been my experience with every other company I've used this feature with, to receive a proof the next business day. It has now been 5 days since my order and I still do not have a proof. This has delayed my order past the date needed to receive the product in the time that I need it.  This in and of itself is extremely frustrating and disappointing, but more than that I feel helpless trying to work with this company and resolve the issue. When I did not receive a proof in the time that I knew I needed to, I attempted, and continue to attempt, to try and reach out to this company for assistance and getting the process moved along. After 3 days the website indicated there was a note on my file that was delaying them moving forward, however, there was no way to view the contents of the message from what I could tell so I had no actual idea what was wrong with my design. I also was not alerted that there was a note, so whether it had been sitting there for 2 days or had been posted that day, I have no idea, either way, this is extremely frustrating, as I would like to be notified asap if there is an issue so that I can fix it immediately; isn't that the entire point of requesting a proof? It wasn't until I got a response via email with the contents of the note that I knew what was wrong and could update my file. However, once I did that, there was no way to update my order on my end or indication from them about what to do next. There was an upload new file button, which I was unable to utilize because I used their online design tool for my boxes and did not have a file to upload.
I made another attempt to call customer service and was finally able to speak to an agent who was friendly and technically helpful, however, she told me she got my new design over to the file specialist and I would receive a proof within 1 to 2 hours, a rush from the usually 6 to 12. It is now the next business day, past the 12 hour, max time promised and I still have yet to receive a response, a proof, or any indication that this company cares about my order. I have left messages and emails which have all gone without response, so as someone who doesn't make a point to publicly express dissatisfaction, I feel like this is my last resort at getting through to someone from this company that might be able to help me. 
I've never had such a frustrating or disappointing customer service experience. Review collected by and hosted on G2.com.