Garanti BBVA Amex Card Suspicious Transaction and Unauthorized Access

In November, there was a suspicious transaction of 0.1 USD on my AMEX card, followed by a significant charge of 817 USD a few hours later. As soon as I noticed the transaction, I engaged in a video call (a great convenience for someone living abroad). The representative informed me that they couldn't handle the dispute, and I needed to initiate it either through their application or with UGI. We closed the cards, and I was told a form or file was opened for me. After interacting with a robotic system called UGI, I was connected to a live agent. We explained the situation, and while they acknowledged the suspicious charge and assured it would be addressed, they advised that for me to dispute it, the charge should not be in the pending state (contrary to my belief that disputing a charge is easiest when it's pending). They assured me they had initiated the process, and my disputes would be evaluated within 20 days, and I would be notified via SMS and EMAIL. When my statement arrived, the charge was still there. Upon contacting them, both in video calls and with the UGI, I received assurances that I hadn't initiated any dispute. It seems I had mistakenly closed my cards thinking everything was in order. Due to my location abroad, I couldn't reach 085022033, 444033, and similar numbers from my regular phone; instead, I consistently received an error signal. After lengthy discussions from a different phone, I spoke with each department, covering card transactions, internet operations, application errors, etc. When trying to reapply my dispute through the application, I could view all my charges as disputable for that period, except for the suspicious one on one of my cards, my new MasterCard. Thus, I couldn't proceed with the application. During the call center conversations, they admitted it was a system error, opened a form, and advised me to check the form's status the next day through "internet support." I followed their advice but was then asked to visit the branch, the most challenging task for me, given that the nearest branch is 4000 km away. I have been trying to reach Burcu Hanım at my branch for three days without success, despite leaving my phone number. My fear is that, after all this, if I don't manage to resolve things in a timely manner, I might end up with significant financial losses.