I've used Agoda quite a lot, and have only ever had one issue with them; this year, I booked a hotel room in Incheon the night I wanted to check-in (using ICN's free wi-fi). Well, the reservation went through as confirmed, and the ICN info. desk begrudgingly helped me call the hotel to ask for a shuttle, but the hotel manager yelled at me and said NO ROOMS. Wonderful. I emailed the Agoda customer service and within the next day or two cancelled the reservation, and refunded the money shortly after. It worked out because that room would've been around US$100 (for a load of rubbish), but I found a room with a water cooler in Bupyeong for around US$35.