Titan Company — battery replacement in titan edge

Address:

World of Titan, kiit road, Patia, Bhubaneswar, Khordha, Odisha, 751024

I asked to change the Battery of my Titan Edge at the WORLD OF TITAN STORE at Plot No. 516/1755, KIIT ROAD, Patia, Bhubaneswar-751024, which was done vide Invoice No. [protected] dt. 15/03/2020. But, I was given a bill for Rs 477/- and was asked to pay whereas the normal charge for battery change in all other shops happens to be Rs 70/-. While no satisfactory answer could be obtained from the staff concerned on my query for the reason of the high charges, I got astonished when I went through the bill after coming back to my home, wherein the product description was written as 'SERVICE CHARGE INCLUDING BATTERY PRICE'. I couldn't understand what Service was done for changing a battery & furthermore, I couldn't know what was the actual cost of the battery.
Yes, such high charge was not communicated before carrying out my order & as a result, I had to rush home again to procure cash to pay the bill with lot of anguish & embarrassment too.
I very much believe, no satisfactory answer I will be getting on this.
Thanking you.