Health insurance tax credit overpayment

I’m self employed and my income for 2021 ended up being *significantly* lower than the reported estimated income used to apply for medical insurance tax credits. As a result, it’s looking like I’m going to have to pay back the full amount of tax credits I received which is going to end up being more than I even earned this year (it was a REALLY bad year). My insurance agent said I can reach out to the IRS and ask them for leniency but I don’t even know where to start. I feel so overwhelmed and devastated. This is going to put me in significant debt on top of an already abysmal year and with student loans resuming in January I don’t know what I’m going to do. How do I go about finding out who I need to speak with at the IRS?