I can but guess.
I trust you have some form of contract whereby some minutes or texts are charged at a lower rate but after you have used them up any more is charged at a higher rate ?
Unsure about the 16.80 but I'd guess you made a 3 minute 0 second call that was charged at this lower rate, and also sent 3 texts again charged at a lower rate.
That'd be my guess anyway.



