Nokia India — give me phone of another imei no.. cheap service.. mental harassment

Address:

Pune, Maharashtra, 412105

Hello,

I purchased nokia 8.1 2 months ago as my phone meets an accident it gets scratches on screen so i give it to nokia service centre i paid rs 9000 and make it cleared. But after that i was facing network issue so i again submitted it to service centre he kept my phone for almost-10 days and after that as he gave my phone return i got to know that it's of another imei no and another specifications. My phone was of 6 gb ram & 128gb storage and the phone i received is of 4 & 64 combination.
I have 3 concerns..
1) my phone was all ok but after changing display only it was facing problem
2) i submitted my phone on 20th august when i asked him for job sheet id he gave me old one means he did not open my job sheet i'd also
3) and gave me wrong device
4) i complaint it almost 4/5 times.. No action taken
Now what can i do?