Free trial problem / not free

To whom it may concern,
I selected free 7 days trial inside the application and I ended it before the last day but even though it was a free trial and I ended it before the deadline you charged 30,99 TL (amount for 1 week) from my credit card.
I thought maybe I was late to cancel it and with that payment I can use all features 1 week more but no, features have prices again.
In the summary, I want my money back or logical explanation for this problem.
“Do not use free trial, it is not free!”
With regards,
Ceyda

Killer episode 1 about Recolor - Coloring Book, v4.2.3