The most recent three dongles install themselves as a network card and do not require any further software. I made a similar move about a year ago and found that my old PC ran much better without the Three Connect software. The only drawback is lack of text messages from 3. Incidentally I made further improvements by purchasing a TP-Link 3g router and removing all software related to the dongle from the PC. Connection is now by Wi-Fi
What is ransomware and how do I protect my PC from WannaCry?