Stanley Mug Started Leaking After 5 Months

I purchased a 0.35 ml Stanley mug from the A101 Extra Kapıda application in September 2025 and have been using it for about 5 months, mainly for hot drinks in my daily routine. After this period of normal use, the mug started to leak, which is absolutely not something I expect from a product of this brand and at this price level. After the problem occurred, I contacted A101, and I was told to send the product to Gurur Tekstil's technical service. The product was examined, and a written response was sent to me. However, this letter is not clear or professional at all: there is an unsigned stamp/signature, but no date, no file or record number, and no detailed technical explanation. It is simply stated that there is no problem with the product, but no clear justification is given. I do not find it acceptable that an internationally reputable brand like Stanley and a large retailer like A101 base their assessment of a leaking product on such an incomplete and non-transparent technical service letter. I paid 999 TL for this mug by credit card, and I am currently unable to use it due to the leakage problem. I request that my grievance be remedied, the product be properly re-examined by an authorized and competent service, and that I be provided with a clear and reasoned written response. If the defect is confirmed, I request a refund or replacement of the product as soon as possible.