Yu Yuphoria — Not get the phone form service center, which is given by me in warrenty period plz help me

Address:

Gwalior, Madhya Pradesh, 474005

My name is deependea singh from gwalior -474005
I brought yu yuphoria cell online from amazon (1 oct. 2015) and after three months the lock key is not work properly, then i decide to submit the cell on service center on date 02- mar.-2016 and they told it takes only minimum 15 days and maximum 20 days and new cell phone is dispatch at your home then i said ok and they give me a jobsheet (Jobsheet no. N[protected]) and today is
14- apr.-2016 i call in yu yuphoria service center almost 20 time every time they it takes just 8 working days, 15 days but every time they just made me fool
So please help me and take a urgent action on this serious issue