One of the main disadvantages of shopping online is the absence of a clear refund policy for most online stores. Some offer store credit if they are unable to ship the item, in other cases it is impossible to track the transaction and you do not know where the money has disappeared . A few ecommerce sites will refund the amount back to your credit card. It some times takes more than a month for the amount to be refunded.
A few days ago, the VISA and Mastercard servers were not working properly, so online payments using credit cards / debit cards were getting rejected. Some problems in debit/credit card processing persist till date.