Pepperfry — Incorrectly charging cancellation

Address:

Online

On 7th Feb 2024 I ordered one Mattress from Pepperfry with:
Dimension:
72 L x 72 W Inch
Thickness:
6 Inches
Brand Spring tek
Immediately after ordering I realized that I didn't selected right dimension which I was looking for (78*72) I tried to cancel the order and reorder with correct size.
While cancelling I saw that they are going to charge 2.5 percent transaction fee which was no where mentioned while ordering the product.
This is highly unethical to charge a customer on the same day of canceling.
I tried to connect with customer care and didn't get proper resolution. This kind of company need to stop cheating the customer on the name of policy.