Splitting of connection

I have signed up for 80GB monthly connection using the Huawei wifi router provided by airtel. I am not happy with the connectivity of this router as I do not get coverage in certain areas of my house. Is it possible to connect another wifi router to this already existing router, in order to enhance the connectivity.

Yes. In this setup, the extra router will be known as an access point. You can also buy a wireless extender.

Any router that can function as an extender can be used for this. Or, if you are looking for a software solution, have a look at Connectify.me.