Need some help with questions on billing cycle and plan and what happens when it changes

Hi, 

So I did read Sqsp's help page on what happens when you change plans/billing cycle but I'm still not 100% sure.

So if I get a business plan and ask for annual cycle, what happens if I change my mind in the middle of that annual cycle and want to do Personal plan for example. I would have paid for entire year's worth of biz plan already, would I get the math all worked out by sqsp and get a refund for the gap between Biz and Personal for the year and then the following year I'd pay a whole year's worth of personal? Or would I not get anything back and then just have overpaid for a swap to Personal?

And also what another even more complicated scenario, what if one changes from biz to personal AND annual to monthly?

Thanks in advance!