Dell India — declined warranty of monitor saying that it is a fake product

Each time i call them they are saying wait for 48hrs and after 2 week they said that invoice in invalid,
After resenting the invoice picture they took other 2 weeks and finally after lots of calls by me they said that the monitor is not a dell made one and hence they cant provide me the warranty.
The store from which i bought the monitor says that the warranty is claimed by a centralized service from dell through this kind of call centers
So i am unable to replace the monitor
Its more than 2 months now and still they are saying that issue will be solved within 24 hrs