Confused with 'unless'

[macenglish]

Hiya,

My teacher said that this sentence in my essay was incorrect. I don't understand why:

"In contrast, you would need to go to a mall or call someone to do these activities unless the Internet exists."

She mentioned that 'unless' sounds unnatural here. Could someone tell me why 'unless' is incorrect here?

Thanks!

[Alan]

Presumably you intend to say: ...IF the Internet DID NOT exist. (a second conditional).

Note that 'unless' is not identical to 'if not' (although that is a convenient way of simplifying it for learners) but rather means something like 'except in a situation in which'.