BMW 5.20i "Replace Battery" Problem, Out Of Vehicle Warranty

My 2021 BMW 520i, first registered on 03/01/2022, with only 10,800 kilometers, is under a 2-year warranty that extends until 29/12/2026. However, my vehicle recently experienced a battery issue, triggering the engine warning light. Consequently, I took it to Borusan Oto Balgat Ankara authorized service on 13.09.2023, requesting a warranty-covered repair. The vehicle stayed at the service for a day, and they claimed to have repaired it, stating there was no problem with the battery. They performed charging and programming, mentioning that new vehicle batteries can last 4-5 years without issues. However, two days later, my vehicle displayed low battery warnings, struggled to start, and the engine warning light reappeared. I returned the vehicle to the same service with the same service consultant on 21.09.2023, expecting a warranty repair. Surprisingly, they informed me that the battery needed replacement, citing disuse as the cause, and handed me a proforma invoice for 12,394.46 TL. I am puzzled as to why I was informed that the repair process was under warranty on both 13.09.2023 and 21.09.2023 for battery-related issues but then charged for the battery replacement. According to the Ministry of Customs and Trade's warranty certificate regulations, vehicle batteries have a minimum 2-year warranty, regardless of usage. This issue seems to occur in new vehicles purchased from BMW and Borusan services, where they charge for battery replacement. While other battery brands unconditionally support their products, it's disheartening that globally recognized brands like BMW and Borusan handle this situation in such a manner. I request a free battery replacement under warranty to resolve this matter.