Easemytrip - Reg Improper billing

I was searching to book a flight from one place to other for * passengers. I did not find charges economical in some flight so I tried Easemytrip to book my tickets. Initially I noticed charges were more so I started searching other options but I saw a discount of Rs **** plus in easemytrip portal suddenly so I decided to book the same. When I completed all details and show final amount was something near to **k plus then I decided to proceed for payment . When I paid through Google pay I got to notice some additional charges got added where my total booking amount reached to **k plus. I talked to customer care of easemytrip and they were trying to convince me that some convenience charges added in final amount. Here is my question, why such convenience charge not added while amount **k plus reflecting as final amount and when I paid through Google pay how could lateron convenience fee added to it. During this covid there is no convenience. I felt like being made fool .