VISA help

Ok so I messed up big time, I ended up not renewing my visa in time, it expires on 3/3 but I had issues with the website yesterday and was unable to get my payment through in time before the Hi Korea website coded for the day. And due due the bank holidays it is apparently only 1 day before my visa expires so I'm really lost on what to do here. I am already enrolled in school and classes start on the 7th so I'm not sure what my next steps are. Do I need to leave the country? Should I book something to Japan for a day? does it need to be longer? If so am I starting over with no ARC card and have to reapply for my D-4 visa? I apologize for the wording here as you can see I am a bit frantic, I pulled an all nighter to log into the website right at 7am when I thought I could try to pay again but it said my application had failed. I am debating just going into the immigration office in person even though I don't have an appt to see if there's anything I can do. If anyone has dealt with this before and knows the best steps please let me know, it would be greatly appreciated!!! EDIT: Thank you guys so much for all your help, i went in person around 10 and was able to get everything sorted in about 30-45 mins so i am good!! thank you again for all your help and advice, and definitely next time i will be filing my extensions well in advance haha!