Xiaomi India — poor service since 1 week

My redmi 4a was dead, therefore i went to repair it to the mi service center. There, after a long standing in queue for 3 hrs the engineer took the handset for repairing and told to wait till it get repaired. Then i waited for more 2 hrs, and then the engineer gave the phone. At that time the mobile was perfectly working and then when i came home the handset was automatically switching off and again restarting for mostly 10 times. The next day again i went to the center and again waited for 3 hrs and the engineer gave the handset and told there, it is repaired and at there only itself i used it and after 4 to 5 minutes it again switched off. Then the engineer told to keep it for a day so i again went next day to collect it but he told that it isn't repaired yet. He gave the handset and told to come after 6 days because of diwali holidays. Now whole the day should we waste our time in this only?