Elizabete
Have you ever considered checking the General Terms and Conditions of the HF+?
If not, the question which tickets can be bought with it is also reflected in the specific => FAQ
In short, the discount/bonus you can get with it applies to personal tickets in Switzerland only. You could however consider splitting your ticket and buying the Swiss leg until Geneva/Basel with it, in case it makes sense from a financial point of view.
Can you buy tickets in CH with the HF+? If not, review the question about Activation in the FAQ I linked above before seeking help with SBB (customer service or ticket counter).