Robin,
If your mastercard is a credit card then you can switch to any credit card you want. Loads to choose from, you\'d need to make your mind up as to what features were more important to you - lower APR / cashback scheme / loyalty points. Good info etc on moneysupermarket.com but always check the smallprint.
If the master card is a debit card, then it operates directly on your HSBC current account, so you could not switch it without changing banks/accounts, unless you believe the card is faulty, in which case the bank should replace it for you.