Unfulfilled Promises by DeFacto

I received a 400 TL discount on a 1500 TL purchase of children's products through DeFacto and Bonus. It was stated in the descriptions that it could be used both in-store and online. The cashiers at the Izmit outlet store, however, were unable to apply it that day and later claimed it was only valid online. However, my bank's campaign terms state that it is also valid in stores. Following that, DeFacto acknowledged my request and called me several times. They then fell silent. When I inquired about the issue again, they stated that I had never made such a request and that it had been closed without resolution. I'd like the 400 TL discount applied to my Gift Club account so that I don't have to bear the brunt of your incompetence. You've launched a campaign, but neither you nor your cashiers know how to put it into action.