I'm interested in possible links between contract termination date & sudden problems with all Samsung products? 4 years ago I bought a new Samsung S7e from Car Phone Warehouse. During the last 6 months on my contract my phone developed problems, everytime I updated. Issues with charging, moisture ingress, Security problems, etc... I love my S7, so decides to keep it, and bought a new S9e to use for work, and keep my S7 just for personal use. I switched the S7 from EE contract to EE pay as you go. To my surprise, all the problems disappeared!!! Same charger, same everything just a new sim. My S9 has worked perfectly until my contract became due for renewal. Same old issues, charger, USB port, moisture, fails to charge, wont switch off... all after the last update!!! Coincidence, or are we all being processed into the conformity of renewal?
This has been a subject broached quite a few times over the years and not just on Samsung Phone's @FishmanAGD
We all know what Apple did to their iPhone's so that they accepted the newest iOS ! 
Issues can occur with phones especially if there used for longer periods of time. They accrue broken files, junk files etc and the batteries output tends to decrease.
I personally make sure I keep up to clearing out old files and caches etc and don't download apps that I really don't use or are not productive to me.
Sometimes even the sim card can cause issues hence when you swapped out to Payg this may have helped resolve some problems - who knows
I tend to use a phone for 2 years max and swap out for my own reasons.
In my opinion Samsung don't affect their phones negatively via software and security updates to steer a person to upgrade.
Again my own personal opinion.
🌈 Stay Safe 🌈
