Help Stoltzfus in PA sold us a brand new leaking camper!

We did an inspection yes, but the leak from the tank is a slow, slow drip and the garage where we did the inspection was wet due to the filling of the tank, etc. And the condensation and leaking happened during the rain, so we couldn't see that prior to purchase. We trusted that a new product meant it would be new, no issues.

The credit card company said we can dispute and get them to take it back, but we want to have it fixed. Is the leaking problem under the mattress fixable? Is some condensation normal?