Sony Mobile — Too much delay in delivery

Address:

Ambala, Haryana

Dear sir
On 1 feb i purchase a sony mobile experia u st125i
But when i insert sim in mobile mobile geting auto restart ande display are blank . On 4 feb i visit at sony service centre in ambey electronic and recieve a deo against my defective set. They assured me that they provied me a new set within 5-7 days but today 13 feb i have no recieved mobile .Maney times i call at service centre and also coustmer care but no response . They repate same thing from 6 feb
To till date that your set is deposit to our warehouse.
I have no satisfaction from coustumer care and also service centre.
Every time i get a call every time i hve to give three to fourdays time
So please help me becfause i am fell total helpless