Google says I have an existing AdSense Account but this is my first time ever creating one - Help? 

I am a fairly new YouTube Creator who has just recently met all the eligibility requirements needed to apply for monetisation on my videos. So, I applied for an AdSense Account but received an email the next day from Google saying that I already have an AdSense Account linked to my YouTube Channel and that I would need to close that one first in order for them to set-up and use the one I just recently made. However, the problem with this is that this was my first time ever creating an AdSense Account and I had definitely not previously made or linked an AdSense Account to my YouTube channel before as I only just met the new requirements that YT put in place.