Unwanted upgrades

[jrwagh333]

I am just curious as I see a lot of these 'unwanted upgrades' for sale in the mobile phone thread.
I am due an upgrade, but I chose to keep my phone and go SIM only on the same network, as I got more data for less money.

So if people want to keep the phone they have, why don't they just go SIM only instead of getting an upgrade? As all the upgrades I have been offered would cost me more per month

 

[jrwagh333]

I have yet to be offered an upgrade at the same price though. It's always more expensive per month. That's why I was mainly curious about why people do it.