Petrol — Fuel quantity misleading

Hi sir/madam,

Complaint on shell petrol pump, near uppal stadium.

I own ecosport car, i filled diesel 2 times tank full.
1st time - distance to empty was 50kms, then tank full cost is ₹3964.
2nd time - distance to empty was 33kms, then
Tank full cost is ~₹3630.

Inspect of having less fuel second time cost is less by ~300.
I didn't understand why.
If there is any time interval mileage gap also there should 1liter or 2 liter difference which costs 163.
So, i bought there is some misleading setup for fuel quanity or price.
I request you to check so that we people get some confidence.

Thank you
Anirudh