Unauthorized Debit by Yapi Kredi Bank

Yapi Kredi Bank took money out of my account without my permission and called it an "automatic principal collection." When I called customer service to ask a question, the representative who took my call was unable to answer my question and instead connected me to another department before ending our conversation. When I called the bank for the second time, I was met with the same lack of response as before. It is not clear to me why this debit was taken out of my account or for what purpose it was used. The realization that no institution, not even the bank, can be relied upon is disheartening.