Return Problem with NYX Professional Makeup at Watsons

On February 10, 2023, I purchased the NYX Professional Makeup Bare With Me Concealer Serum from Watsons Online. Within a short period of time, the pump of the product became faulty, rendering it unusable. I initially reached out to NYX customer service to report the issue, but they directed me to contact Watsons. On May 11, 2023, I informed Watsons about the problem, and it has been a frustrating 2 months since then. Despite numerous calls, they have failed to provide any response. About 2 weeks ago, my return/exchange request was approved, and I was asked to send the item back using Yurtiçi Kargo. However, when I went to the courier, they informed me that the provided return code was invalid. I contacted the call center, and they suggested contacting the 2307 Mermerciler branch. However, they stated they no longer handle such matters and advised getting a new return code. I informed Watsons call center about this, but they said they couldn't provide another return code and would escalate the issue to the relevant authorities. However, days passed with no response, so I contacted them again, and this time they informed me that they had an agreement with MNG Kargo and provided a return code for them. When I went to MNG Kargo, they asked for an approval code, which I did not receive. It has been 2 months, and the situation remains unresolved. This has been my worst shopping experience. I can't comprehend why Watsons is delaying the resolution of my return.