Physics A Level Module 4 HELP

So I am doing some self study and obviously, as temperature increases electron kinetic energy increases, as that is proportional to v^2 average drift velocity increases but this increases the rate of collisions.
When the temperature increases to the thermistor this gives enough kinetic energy to the electron charge carriers to break free, but with my above explanation doesn't that mean that the resistivity should therefore increase? This is self study (teacher is a bit mid (emphasis on the bit)) before we go through it in the lesson can someone just explain pls.