Korea Sim went above and beyond to help me during my trip. I had purchased a Blue LTE sim which for some reason would only connected to 3G. After various failed attempts to connect to the LTE network, I was content with using the 3G network for the rest of my trip but was told by staff that I paid for LTE and deserves to use LTE. They went out of their way to reset the values for me and by day two I was on the LTE network! Definitely recommended!
Facebook review - Kathy Zhao