You're right. That scenario is pretty ugly. I would suggest, to talk some sense to your wife and discuss things properly, since we wouldn't want you getting into trouble. Just present her your numbers and not just word of mouth. Women are not so much into "math" (majority) and can't really make an informed decision as to what "practical" is. Of course, unless it says "SALE" on it.
Work your numbers, probably use a spreadsheet. Label columns correct to identify which are the amount spent (expense), proposed carrier and their monthly subscription and savings in another column. Women need to see the numbers. They need to visualize to make more sense on what you are saying, especially when it comes to their "wants" and "needs".
Good luck!