I kept getting this error:
"An error has occurred. Please try again. (CSA_0018)"
when trying to activate a new account.
The useless help support staff were NO help!
After a good deal of attempts I decided to install the rapport software (adds Trusteer to your computer - I did not want this, just like many others wont), however, it then activated first time.
Shame the HSBC support staff did not know what CSA_0018 meant! (it must be sacred info only understood by the Indian programmer that coded their login!!!)
Hope it saves you some time, and helps reduce the frustration.