Sony Mobile — service centre fraud attempt

Address:

New Delhi, Delhi

i submitted my sony xperia j at a service centre in delhi on 26th november.it was in good condition, only its mic wasnt working.they submitted my phone under warranty.3 days later wen i contact them they show me my phone with a cracked screen.they broke it n said it was like this wen u submitted it.are they kidding me? how can they break my phn n then put it on me then? after my shouting on them they agreed to repair it.so plz tell me guys shall i ask for a new phone or extended warranty?