Once, decades ago, while traveling with my closest friend, I encountered that exact situation (far too late) in a cheap Motel 6 loo. When my buddy (outside the bathroom) followed my yelled order to call the front desk, the clerk’s appallingly unhelpful response was “I can get you a new roll in one hour”.
Suspecting that he’d misquoted the clerk and was viewing my predicament as humorous, I yelled again through the closed door, “The cleaning staff will just have to assume we stole these two washcloths because they’re going straight to the motel lobby’s rubbish bin, wrapped in one of these two clean towels, which would have been
your towel, by the way.”
He got the intended message and quickly responded by opening the door just wide enough to pass along two fresh rolls of toilet paper which (as I would later learn) had been stored neatly on a small shelf just outside the bathroom all along.