Civil demand letter

Location: IL
I got a civil demand letter from Michael Ira asen asking I pay 500$ in a civil claim and 222$ in restitution due to me stealing from my previous employer
I admitted to stealing but the amount was never over 20$. while I spoke to whoever conducted the investigation they did say I would have to pay them the 222, but they never showed me any documentation regarding how they calculated that number and they also stated they would pursue any legal action if I was cooperative enough and payed them back I took accountability for my actions and apologized and I’m willing to pay them the 222$ so they can just leave me alone even tho I didn’t steal anything over 20$ but the 500$ civil demand is crazy I feel blindsided

Does anyone have any advice for me?? Anything is appreciated. I already emailed them asking for documentation regarding how they calculated those numbers
Also the letter does state to pay within 21 days so no further legal action is necessary