T-Mobil sent me to collections by mistake, can I sue for my wasted time?

I switched from T-Mobile months ago with 0 balance on the account however I received $140 bill via mail. I called the number on the letter and the representative told me I used the line for like 7 days, she can reduce it to $80 since I didnt use the whole month, I accepted and paid it. 

2 months passed now I received collection letter from T-mobile for the remaining $60 balance, I called T mobile , 3 hours on the phone, representatives told me account is already sent to collection, previous representative did not waive the $60 on the system. I am being told that I should wait for collection agency to contact me. 

Now I have to spend more hours on the phone for a $60 bill, and if they already sent collections report to the credit bureaus, I have to deal with dispute process. I was also planning to apply for auto loan this month, too much headache and wasted time.

Why I am the one being punished with my time and money for T-Mobile system or representative mistakes? Can I sue T-Mobile after all these collections process for wasting my time and get some compensation?

Appreciate any suggestion.