Nokia — delay in rectifying the problem and software updating

I have provided my nokia 5.1 plus with a problem not working due to the software corruption. I have provided the mobile phone in an authorised service center of nokia in trivandrum, kerala, india. Its name is geecell-tri (531_465550), second floor, blue tower, power house road, trivandrum. 695036. They have taken the mobile on[protected]. But today is[protected] till this date if we contact them they never pickup the phone or reply to the calls. They have taken more then 1 week till now with no response. I dont know what to do. I am providing more details below.
Job sheet number :[protected]/200528/017
Contact of the service number : [protected], [protected]