Nokia India — misbehaviour of nokia authorised service center people

Address:

Tirupati, centralpark

I given phone to them for software update. They r not giving back my mobile. Simply they r saying that u can do anything we can't give back ur mobiles. Simply they r talking like street roudyes. How can ur authorised service center people behave like this. How can i get back my mobile.
There is so many issues like this with these service centre people. How can nokia selected these type of people as authorised service center. Still i have receipt with me. They collected my mobile and bill to update in varanty, now they r abusing us if i ask my mobile. They r behaving just like street roudyes. Make justice to me