Switching from rogers and Wondering what to do with my bill

So I moved last month. I had bell in my old house and my new house I got a deal setup before I move to start on the 2nd of AUG with rogers. The place I moved to has a bell referral program so I seen what it was. I'm not switch back to bell but I got my bill today and seen I got bullied for the 2nd of AUG to 2nd of SEPT and also billed for Sept 2nd to Oct 2nd. I didn't know rogers billed a month in advance nor I was told. My services is being switched back on the 13th and I'm wondering what will happen since I'm not going to pay for half a month of bill I'm not using. Rogers phone support are currently too busy everytime I calls.

Will they just pro rate it back to half a month pretty much or will I get a credit. Do anyone have any experiences of what will happen.