Xiaomi India — fraud done by service centre not got my phone back

I have given my phone redmi note 8 pro brand new phone for black screen problem before lockdown on[protected] they told it's sensor problem it will take 2-3 days as parts are not available after that lockdown started and i didn't got my phone after unlock i visited service centre on[protected] and they told come tomorrow as phone is still not repaired so i visited next day and service centre was lock and it's still locked i think i have got cheated please help me get my phone back i have original service receipt of service centre.