Mi Redmi - Exchange mobile fraud by mi service centre

I went to mi service centre located at *st Floor, Legend Plaza, Opp SBI Main Branch, Uttar Pradesh ****** , nearly a month ago to get repaired my mi redmi *s. It just had a charging issue.
I was told first to collect it in *-* days. It took more than a month. And they said that there motherboard problem.. Going to send it to company then later told me that phone is dead . can't be repaired.. When i told them to give me my dead mobile . they searched it for * hours and then told me that they haven't received mobile yet. Told me about mi exchange offer.. And pressurised me to buy a new phone.. They said that if you buy a new mi phone . nearly **** rupees off on new mi mobile.. They said every thing is official and company offer.. They told me to give brand new mi redmi note * **gb in **** rupees.. I agreed.
After five days i came and they give me a mobile with no bill , no box and with no accessories , when i asked about bill and every thing else. They told me that this os company policy and you will just get a phone in exchange.
I took phone and went home.. I was in a bit suspicion. So i called mi customer care.. They told me that company has no policy like this. Mi service center don't have any authority like this.. When they asked me my mobile no. Which mi service centre showed to registered for my mobile for reparing.. Mi customer care told me theres no information about it. When i asked first activation date of this redmi note * **gb model they told me that it was a old phone activated in **** .. While mi service centre told give me this phone on August **** on the name of brand new phone.
Mi service centre has done fraud with me.. Plz help ..
The name of the person done all this working at mi service centre is Vaibhav dang .
Phone no. - **********
- **********
Plz plz help me..