LGU+ cancellation fees.

Hello! I am leaving Korea this summer so I'm trying to make a list of things to tie up before leaving... when I came here seven years ago, I took over an internet contract that the previous teacher had used for three years. I was told I was saving him a hefty cancellation fee... I'm now wondering if I will have the same issue. I read that they charge up to 600k for cancelling! Even after ten years of paying for service? Seems insane. If this is the case, I'm hoping to find someone to take over as well, but obviously it would be simpler to just cancel the contract.

Does anyone have experience cancelling a plan with LGU+ where they didn't pay a fee like this? And I've never found a great customer service line for them unlike other services I have here. Does anyone have a phone number they have used to communicate about something like this? (Preferably with English services, but if not then I can speak Korean alright).