[Osem]

Just an update on this. I still have the phone and it's working fine. I disabled the android.cube preinstalled app which appears to be at the root of this issue but discovered it relaunches itself every time the phone is turned off/on. I now leave the phone on, avoid using it on Wi-Fi (because the rogue apps only appear via wi-fi) and stick to mobile data when I need it which isn't often. The problem hasn't reappeared.