I am not gettign my phone from service center

Location/place: Noida

Name of company/service: Sony Mobile

Hi,

I have Sony xperia ray(ST18i) mobile having IEMI no 358343043846163, I sumitted my phone on 30th april 2013 on service center for reparing but till now i am not getting my phone back. Please do some useful because i face too many problems without mobile phone.