Pegasus Airlines Birthday Discount Promotion Not Applied as Promised

I attempted to purchase a ticket with Pegasus Airlines, expecting to use a 20% birthday discount that was mentioned in an email. When I first checked the fare, the discount was visible. However, when I proceeded with a second search for a different date, the discount disappeared at the payment stage. I called customer service, who suggested trying a different search approach to apply the promotion, but this still didn’t work. After further attempts, they advised creating a complaint but discouraged purchasing the ticket for now. Meanwhile, each search only increased the fare. Since the price lock was about to expire, I was eventually told I’d need to buy the ticket without the discount. This promotion is misleading if it can’t be applied. Pegasus, please honor the discount as advertised.