Yu Televentures — imei lost after resetting the phone

I bought yu yunicorn device which seems to be slow and then i called customer helpline. They instructed me to reset the phone. After doing the same, my phone doesn't get the signal. When i have taken the phone to micromax care (M/s lakshmi communication) in tirupati, they asked me to pay 400 for restoring the imei. I've asked them to restore old imei. Still they are asking 200 for each imei, 400 for both. What's my fault in this. Kindly do something on this