India Post — charge more than printed in docket slip

Address: Haridwar, Uttarakhand, 249401

Yesterday i post my official document by speed post
From haridwar post office pin code 249401 counter no: 1 op code :22
Rs. 71 is printed in docket slip as i don't have change of 71 i give rs. 100
She return me 30 rs. And said to give 1 rs. Change i give 5 rs. And ask to return 4 rs. But she deny to return and said she don't have change as she already have change
I am regular customer of that branch
That employee do most of time if 69 is printed in docket slip she deduct 70
And talk with loose words
Why should i pay from my pocket if i only claim according to docket slip
Kindly look at this matter