String Theory and Narnia

I just can't read books which involve String Theory. My Spidey Science Sense starts tingling too quickly, and I can't get past the initial assumptions. OK, so modelling reality as tiny strings of energy seems to include gravity, and the model requires at least 6 other dimensions of space, and those dimensions must be small because we can't see them. I can get that far. But when the models start to deal with how strings can curl around those 6 dimensions and so on, I feel the urge to chuck the book out the window (which is a bad idea, as it's usually on a Kindle). You can't use an unverified requirement of a mathematical model (the extra dimensions) as justification for further claims about reality unless or until you have verified that requirement. The existence of the other dimensions isn't a requirement of physics, it's a requirement of mathematics. Someone has got their ontology utterly screwed up. 

String theory is like Narnia. Before you start to present ideas about the landscape of Narnia, you first have to show that wardrobes are trans-dimensional and that the specific land of Narnia lies within.