Getir Overcharge for Orders with Incorrect Promotion Application

I placed an order on Getir where there was a promotion: spend ₺400 and get ₺200 off. I ordered items totaling ₺409, including ₺209 for selected items and ₺40 for shipping. I expected to pay around ₺249 in total, but I was charged ₺288. When I tried to address this through live support, I received nonsensical responses. While waiting for a reply to correct or modify my order, it arrived. Later, I asked why I was charged extra, and they mentioned ₺11 for VAT, but the numbers still didn't add up. Upon contacting customer service again, I was informed that one of the items I purchased wasn't part of the promotion. If that's the case, it shouldn't have been listed among the promotional items. Just like in a store, if an item is labeled ₺20 but charged ₺50 at the counter due to a pricing issue, it constitutes a problem. Getir is presenting a similar issue. I shouldn't see an item listed among promotional products if it's not eligible. While a complaint is filed, no solution is offered. I am requesting a refund. We are constantly experiencing issues with Getir.