J.H.
These debt collectors call people all day, get excuses as to why they can't pay, get hung up on and called names.
You're going to call them, give them money, say thank you and hang up.
You'll probably be one of the best calls they have all day! Be happy that you can make a bill collector's day!
(On a side note, I think it's just embarrassment that is making you nervous. You have no reason to be embarrassed. You've told us about not having paid your bills...and we don't hear about this everyday...whereas the bill collectors do.)