Garanti BBVA Misleading Interest Rate Ad

I became a customer of Garanti BBVA because of the attractive 50% interest rate they advertised. When attempting to open a time deposit account, the mobile app initially showed a 50% interest rate. However, upon proceeding, I was presented with a "special" 38.5% interest rate. When I reached out to customer service, four representatives acknowledged their lack of knowledge regarding the interest rates and were unable to provide a resolution. I spent an hour and a half, what a disappointment and embarrassment.