Poor Customer Service and Unfulfilled Discounts at Amazon

I placed an order on Amazon.com.tr and received a ₺150 discount through my bank's promotion. However, I was bombarded with numerous messages and calls from an overseas seller claiming to be the product's seller, urging me to cancel the order because they had listed it mistakenly. Suspicious, I contacted Amazon customer service, only to be told there was nothing they could do except for me to return the item. They also warned that if I canceled, I would lose the ₺150 bank discount, which wouldn't be reimbursed. Despite explaining the situation and expecting compensation, they insisted they couldn't help. I'm now ₺150 out of pocket due to Amazon's lack of action, despite no fault of my own in this transaction. It's disappointing and surprising that such a reputable company would leave me in this position and not rectify a mistake made by the seller.