Can I border hop to Mae Sai for a visa waiver while my education visa is being processed?

Hi, This is a fairly long post as I've got myself in a rather complex situation, even for Thai standards. I came here on my UK passport in October 2018 on a 30 visa waiver, and then got myself a 90 day non-ed with an opportunity to extend it up in chiang rai. My application to extend my non-ed was rejected on wednesday.......apparently because my old work visa, when i last worked here 2 years ago, was not cancelled properly when i left my old school in Chaiyaphum. They said i need to get a signed letter from the director of my old school and also some kind of stamp in my passport from chaiyaphum immigration saying my visa was cancelled (i'm a bit confused about what stamp they're exactly looking for but it might be something about not having the blue "departed stamp" on top of an extension of stay, which i've just found out is actually on a different page in my passsport. i will go to chaiyaphum immigration to see if they can correct it).........Anyway.......I need to get this all together before by friday 25th january, when my current visa expires......If I can't do this in time, which is probable as the director isnt at school until monday 21st, then could i quickly border hop at mae sai and get another 30 day visa-waiver, which would give me a little more time to get this sorted.......? or do i need to somehow cancel my ed-visa first?