OnePlus India — Regarding take more time for replacement of battery (mobile one plus 5)

Today i visited service centre saket new Delhi,
There is worst service ever. I visited for replacement of battery of one plus 5. They told me it's take 3days time for replacement of battery.
That is not good service in today's time.
And I am very old customer of one plus using one plus phone more than 8 years.
Kindly intervene in this type of service.

With Regards
Chandan Kumar
Mob no [protected].
New Delhi