Xiaomi India — mobile repairing under warranty

Address:

Bilaspur, Chhattisgarh, 495001

Dear sir,
When i visited mi service center 1st they told me that currently we have not the parts then someday later i went to mi center because sim slot was not working then they told me we will repair this out of warranty after then when i told them so repair my display and one sim slot is not working then they told me now your mobile is registered out of warranty so you can not take warranty and you warranty expired. It had been only 3 months to buy my phone.
I want fair decision.
And the behavior of service center incharge of bilaspur is very ill mannerd.