To clarify, it was me who suggested that for users who have Kiro ID already, checking out is for $0 (without discount code). This was based on my own experience (and other users). I've pasted a whole set of screenshots previously from my own upgrade (as a user who previously paid and thus had the user ID) where it's visible that there's $0 price for the pro+ plan listed during the stripe process.
Although in our cases we were users who paid in the past but didn't have an ongoing subscription (such users are listed in the hackathon rules as the same category with users who have an ongoing one).
I'd start with providing details of your case. For example, whether you've registered to the hackathon with your ID before or after payment. EDIT: It's been mentioned in your previous messages that you did provide the ID
Let's hope Sara resolves this on her end in the meanwhile. Did you reach out to her like she asked to?
In the case it doesn't get resolved via either Devpost or Kiro channels, I can offer a reimbursement of the Pro/Pro+ difference from my private money, since it was my answer that led you to pay.
Good luck with the hackathon!