Acer Refused to Repair My Tablet That Shuts Down by Itself

My tablet has been shutting down by itself for no reason. At first I sent it to Acer Türkiye technical service. They returned my product without any sense. Then shipping fee was reflected to me. After I got my tablet and cheched it, I saw nothing. Then I got in touch Acer again with TS674844 ticket / work order number. After their inspections/controls, they informed me that my tablet problem was my user defect, so it couldnt be repaired under warranty. This is really ridiculous. Then I understood that, ACER is not behind its product, so I will never purchase any Acer product.