Any one been in a dispute with a store before have any advice?

>Have a bunch of items in my private wearhouse and haven't had a notice to ship on nearly 3 months
>Some pre-order items that should have been released by now, some items already in-stock
>none of these orders are mixed pre-order and in-stock items, even then they have shipped parts of mixed orders before
>Haven't reviewed any notification that any of these items have been delayed, under delivered or gone out of stock through other means

I sent a message asking where my items are and requested they ship them or refund me (which I know they won't do unless they absolutely have to) and an explanation as to where my property is. If they send me some non-answer I'm planning on refusing to pay for my pre-orders (which I don't mind being cancelled) and if they send me a shipping notification with missing items and no refund or explanation for the missing items, I'm refusing to pay the shipping fees, which will force them to refund me, (with a penalty)

What should I do? I don't see why they I should give them more money when the are incapable of holding their end of the bargain.