Hello, Excelsior (presumably from the famous poem about an alpine village).
You need the breaks. The page numbering issue can be solved after you have them in place.

Go into your header or footer in the B section. Select the page number and go to the Insert tab on the ribbon. In the Header and Footer section, you will see Page Number. Click on the down arrow and select Format Page Numbers. In ensuing the pop-up, select Continue from previous section.

You will need to do this for the section following B, as well.

Best,
Ulo