Blower fan flat out!!!

So my blower is running at top speed. I can’t slow it, I can’t stop or switch it off! My octy has climatronic, so when I keep pressing the fan down speed till “off” appears nothing happens, fans still going. I did the climatronic reset (recirc/econ button hold etc) and this did nothing to help. I had the fan out which looks fine, and I’ve swapped the resistor pack(red thing with three electrical connections that screws to the side of the blower housing) this also had no effect. So I guess two  possible things....

1-it’s not the problem 

2-I’ve swapped for another duff regulator (it was from a breakers, so unknown condition)

so any one have have any ideas what could be wrong or how to test the regulator to ensure it works as it should?

tia!