My İş Bankası Credit Card Charged Me ₺2000 for a Mysterious 'Shopping Interest' Fee

I paid off my credit card balance with Türkiye İş Bankası today, but to my shock, ₺2000 was deducted from my account for some nonsensical reason under "shopping interest". When I called customer service, even the representative seemed clueless about this charge. I'm reaching out to the bank officials directly - I demand that this deducted fee be returned to my account as soon as possible. If this doesn't happen, I will continue to pursue my complaint through official channels.