Flipkart — Partial refund credited

I ordered usmle first aid on 24 July 2022
And paid 150 as advance after 4 days they cancelled my order without my consent and credited only 100rs and deducted 50 rs claiming cancellation charges...
The order was never cancelled from my side still I have been charged 50 rs for that
I have repeatedly tried to contact them over chat and call...for 10 days they kept on assuring me for problem resolution, wait for 24 hrs ...48 hrs...etc...
And now they telling they can't do anything in this ...and won't pay my remaining amount ie 50rs