Someone has taken over your identity.
What you need to do is contact HSBC's Fraud Department. As of right now, HSBC may think that you're just being late with your payments, or that you're a deadbeat cardholder. The departments that are contacting you now don't care whether or not the credit card is fraudulent, they just want their money.
However, if you contact HSBC's Fraud Department, or Bank Card Security, they will be able to help you. They can try to pull photos of where the transactions are occuring, and if they can compare then they'll just drop the charges on the credit card. If this doens't work, you can contact the ombusmen of the bank, who will argue on your behalf and hopefully get the charges drop.
You should also contact Equifax and Transunion, advise them of your ID being take, they will make sure no other applications for you go through, and they may also be able to help you with your case.
The only problem I see, is that some banks will only reimburse you for the last 3 months....you've mentioned that it's been going on for 6....
Good luck