For wardrobe assembly services in Istanbul, you can contact local carpentry services or furniture assembly companies that specialize in home furnishing and installation. Here are a few options to consider:

1. IKEA Assembly Services: If you purchased a wardrobe from IKEA, they offer professional assembly services in Istanbul.
2. Getir İşler: This app provides access to various home services, including furniture assembly. You can request a wardrobe assembly service from a professional in your area.
3. Local Carpentry Workshops: Many local carpenters in Istanbul offer wardrobe assembly and custom furniture installation services. You can find them through local business directories or websites like Armut or Hizmet Bul.
4. Freelancers: Platforms like Armut.com or ÇiçekSepeti Hizmet provide connections to individuals and small businesses that offer wardrobe assembly services.