Why was my withdrawal amount reduced?

Most likely your withdrawal has been reduced to match the deposit amount.

We would like to remind you that Visa/Mastercard is a payment system that allows only a refund of the deposited funds.
This means that withdrawal should be processed proportionally to the deposited sums.

For example:

You deposited via credit/debit card $10, then $20, then $30.
You will need to withdraw back to this card $30 + withdrawal fee, $20 + withdrawal fee, then $10 + withdrawal fee.

If your balance has become less than your total card deposit amount during the trading, don't worry - you still will be able to withdraw your funds. In this case, one of your card deposits will be refunded partially.