About not providing bill and mobile battery issue not arises after service center repaired mobile ph

Hii
I have paid ₹3700 for the display replacement of my redimi not 4 mobile (4gb+64gb)
@service center sasaram distt rohtas bihar 821115
They provide the job no WXIN1708160011923 on 16/08/2017
After 2 days they called and said your phone is repaired 
And you have to pay ₹3700
But when I came service center they said some other problem arised which has to be solved so you will get your phone after solving these problems
And pay ₹3700 
I demand bill for ₹3700 , then they refused to provide bill and said our service center is newly opened so when you will come next time to get your phone we will provide the bill
So I said them to write at the page of service order of job no WXIN1708160011923 that I have paid ₹3700 and signed by them
I have taken picture of that service order page 

On 19 August they again called that your phone is ready 
I came service center , they took that service order page .
On that day I agin told to provide BILL
But on that day also thay said that our service center is not providing the bill till now
You come after fews days you will get your BILL
And provided the service RECORD
Which job no is WXIN1708170011167
 I said the job no is different from the service order
They said that on this job no some other problem has been solved

Another case

After getting my phone I came home
Charged phone fully and starts using 
But the phone lasts for only about 5 to 8 hours 

Another problem also arises , the display which they replaced on paying ₹3700 also showing white spots at right side below the screen and the spot is increasing also
 Next day was sunday so on Monday 21st August I came service center and complained about battery problem. on that day thay directly denied that we can't take you phone for service for next one months 
You come after one months (my phone battery backup is so weak and they called me after one months this is mi service center)

I called customer care also but they not solve my problem
I emailed to mi care ,after emailing some little response is from mi team

Thay provided complaint no also 170831007787

Yesterday 01/09/2017 , they called and said that your job no WXIN1708160011923 was cancelled 
Now I can't understand that I have paid ₹3700 for my display replacement and they changed also , then without informing me how can they cancel the service order

 After replacement of display my phone battery becomes very poor
And screen also shows white spots (which is increasing)
If they cancelled my job no it means they have replaced display by duplicate display and my phone battery also not providing proper backup means thay have changed my original battery


And they have not accepted my phone for repair when I went on 21 august2 2017

Thaks