Help replace input in excel spreadsheet cells, when IF statement doesn't apply

I have a spreadsheet that gives costs in my Letters Page (Sheet 2) as the result of IF statements, which picks up data from my Input sheet (Sheet 1). The information that goes in to my various paragraphs in Sheet 2 are things like percentages, product details and price.

This works very well but I want to introduce a choice in the dropdown list for product details, that if selected will totally remove the existing paragraghs with gaps for percentage and price etc in my Letter, and replace the paragraghs in lines B30 to B38 with a set piece of text saying something else, which I can get from a Source page such as Sheet 3.

Thanks in advance

Larry