Xiaomi India — service problem in warranty period.

Dear sir/madam,
I purchased mi note4 on 21/09/2017 from flipkart. Invoice no - faba6q[protected]
I am satisfied much more with it's performance. The battery performance is poor from[protected]. I raised complaint in service centre no - xmin1569 and they replace the battery on free of cost.
After replace the battery i have problem in display. Display become dark frequently than i gone to the same service center and raise complaint. They without saw the phone and told this is the display problem and told outer panel one of the corner is loght damage so we can not change the display in free of cost. I replied to them this is not like a display problem may be a minor loose connection. But they are not listen my words. Now the phone is working well once or twice in a day the display become dark. Please tell me what can i do now.

Display complaint raised on[protected]
Token no-42

Please help me to solve this issue.

Invoice copy and complaint copy attached.