I don't think HSBC will help you if you don't have an account with them. And even if you do, there is a bit of paperwork and expense involved.
Considering the small amounts, if you can open an Argentine account, if may be better to have them deposit your money locally. Then you could simply withdraw the cash on your next visit, even if it is only once a year.
Another option if you have an account is get a Visa/MC with it- then you could use the card wherever you are, and pay it by transferring online from your local account- effectively spending the money overseas without needing to come here.