Vestel Dishwasher Leaking After Minimal Use and Customer Service Refuses to Help

My sister gifted me a Vestel dishwasher for my home. Initially, I didn’t even think of asking for the invoice or any related documents, as it felt a bit impolite to inquire about the cost of a gift. I only have the user manual. Because of this, I contacted Vestel customer service to obtain the invoice for this device and have it issued in my name. An issue has arisen since the dishwasher hasn’t been used for a long time—water leaks from the bottom of the machine when it switches to the washing mode. I don’t know the cause of this problem. Customer service refused to help, claiming the warranty could only be processed with the serial number and making unsubstantiated statements that harmed the consumer. I don’t understand how a device can break down just because it has been unused for a while. I request the invoice and warranty certificate to be issued in my name. Ultimately, I demand free repairs, as Vestel’s lack of support is clearly causing harm to its customers.