My tax return needed to be amended and I faxed my amended return more than 21 days ago. The "Where Is My Amended Return" isn't showing they accepted it. Who do I contact?

My tax return was and is still processing because it was missing Form 1095-A. I faxed the IRS Form 1095-A and Form 8962 21 days ago and am checking "Where Is My Amended Return" online regularly. The site still does not show that they received it. Who do I need to contact to get more information on whether or not they received the forms I faxed them and if there is anything more they need from me?