HOLD OF "UNCLEARED" AMOUNT ON CREDIT CARD

Beware! After they deduct their payment off your card, they retain a "hold" or uncleared amount on your card for the original order amount plus 15%. I can understand the reasoning, but surely this "hold" should be released as soon as the delivered amount is deducted from the account. I've had a "hold" / uncleared amount on my card for more than 2 week! Phoned call centre without success.