What is a cost effective solution for 4 devices?

Hello, this is my first post, but this issue comes round for me every year at subscription renewal time.

I have 4 devices in my household. I have today purchased a 3 user retail license to continue with my Norton 360 subscription on my first 3 devices. After a bit of faffing about with licenses these are all renewed  today as intended, and all is fine. So how can I buy a cost effective equivalent solution for my 4th device?

Chat with support just returned "I'm sorry for the confusion, however, Norton 360 can only be installed to 3 devices and there's no way  for you to purchase additional license. We have Norton products that has 5 and 10 licenses and they are currently on promo.".

I don't want to have to buy another 3 user Norton 360 product and discard 2 licenses/activations, nor do I want to subscribe for an alternative product now that I've just renewed for a further year a couple of hours ago. C'mon Norton, I'm trying to spend a little bit more money with you; I can't be the only four person household being presented with this situation?