Apple India — defective product sold to me

I bought Apple se 64 gb variant in the month of April 2017.
I can say that I got defect product as I found 3 defects in my mobile.

I tried to fix through online service like chat/call etc. But it does not work and finally I reached apple service center.

For the first time they are not available because of technical problem from their end. Second time I gave my mobile to them, they are able to resolve 2 issues by replacing touch screen and they confirmed another defect is a bug and they will work on it.

Unless it is defect product, why will I face such problem and if it is not a defect from apple end why they agreed to change it.

After I got my mobile back from the service center, I identified another issue with google maps which worked perfectly fine before I handover my mobile to the service center.

Unless it is defect product, why is it troubling me these many times and I am expecting a replacement for my mobile.

Best Regards
Sudhakar G
+91 [protected]
[protected]@gmail.com