Charge for seat assignment and preferred seats without any notice!

I made Flight ticket reservations on CheapOair for two without making a seat assignment.  I got the confirmation email with itinerary and "select seats" option. I followed a link in the email, selected seats, for one of my flight(short flight) I saw I have an option to choose in main cabin seat, I selected it but right away I noticed it cost money, it was paid seats. So I didn't continued to next level, I didn't confirm the seats selection and left the page. I thought If I leave the page it will be canceled automatically. BUT I WAS WRONG!! I found out CheapOair charged me 29.90$ for "Enhanced Seat Assignment" that I didn't get any notification that I need to pay it for seat assignment. Seat assignment service suppose to be provided FREE of charge!! I never seen travel agency or airlines charge for seat assignment.
PLUS, They assigned seats by themselves, or I don't know what went wrong, I was charged for preferred seats as well, 115$.
as I mentioned before, I never confirmed the preferred seats, as soon as I realized it cost money I left the page.

I call CheapOair few times to solve this issue, asked for refund... but nothing helped.
I don't know why I have to pay almost 150$ for nothing!

if I would want to purchase preferred seats, I would purchase for long flight. NOT FOR AMERICAN DOMESTIC FLIGHT(I booked 6 flight with CheapOair , from Korea to  Sandie go, Sandie go- Texas(Charged for preferred seats), Texas- Dalls, Dalls-Korea).

People, watch out!
Be aware!
maybe CheapOair offers you cheap flights BUT it's not cheap! they will charge you extra money for everything without notice, and the tickets are not refundable...not proper customer service

If you want purchase flight tickets with CheapOair , THINK AGAIN and AGAIN!