Huawei — honor 9 lite battery problem

I have honor 9 lite 4gb +64gb. Phone working excellent but battery backup is not good. It work only 2 to 3 hours. I'm student of mbbs and i have to use net for my study but the battery backup problem irritate me. Please help me & work on it. I buy this phone in june. And the problem start from september. If the battery backup problem is not solved than what's the use of my 15k rupees. Please look into the matter. Phone not hot but some time it hangs also & immediately switch off. I think the huwai product is good than i buy it but now i think its the total waste of money. Only good thing in phone is that its looking so sexy but battery & other features are not good. Please improve battery back up from 2 hours to atleast 7 hours. Otherwise the phone is good only battery & hang problem make it worst experience. Look into matter immediately.