Bank Of India — transaction failed but money deducted from my account

Address:

w-124,3rd avenue,anna nagar, Chennai, Tamil Nadu, 600040

Hi,
I was purchased mobile headphones through online but transaction failed amount was debited from my account. Still now, amount was not returned into my account. It almost 8 days over. Please refund my amount as soon as possible.
I used by debit card for this transaction but declined the transaction at that time. Suddenly few minutes after, amount was debited from my account. This could be happened at september 12 but now september 21. Normally 3 to 4 days only for refund the money into account. But, this time almost 8 days completed. When will you refund the money.