How to pay back mainland credit cards in Hong Kong?
Is there an online bank of China Construction Bank? If you can, it is the most direct and convenient to repay money from CCB's online bank, and there is no handling fee.
Hang Seng's online banking should also be able to pay back, but you should ask about the handling fee.
Then give the card number to your parents or friends, and ask your friends to help you deposit the money in CCB's credit card without a card.