For those that know or are studying German, it seems as though 'bensi' is very similar to 'sondern' where the first half of the sentence would contain a negative (I do NOT have X, BUT...).
For example*: (it)Non abbiamo una mucca, bensi un toro. (de) Ich habe keine Kuh, sondern einen Stier.
*non-native, so if there is a better way to explain, please do.
It isn't totally correct if they want you to understand that "bensi" means more "but rather" than just "but (ma)"...but if they haven't indicated that sufficiently during the hints, then you should report it.
Me, I just was told that "We haven't a cow" is missing the word "got," so I have (got) problems too!