Xiaomi Redmi - Screen was damaged by service centre

My mobile Redmi *A is not yet completed one year. My mobile was not charging.Next day my mobile was taken to authorised service centre.He told me to change pin.after that he told screen is not working. my mobile screen was damaged by service centre.Service manager was given report to Xiaomi . my mobile there is liquid damage and physically damage had given report to MI.From last ** days continues giving mailing.yesterday manager tried to do fraud with me.manager calls me and told me it covers under warranty and do sign on paper.after reading that he wrote on that mobile is not cover under warranty.After telling that y u did that like he is not giving any reply.pls give me solution how to cover under warranty.or else another way is there to lodge complaint through police station by doing fraud with me.