Painted condensation wall and it won't dry?

[NattyBeaker]

We painted an external wall in our kitchen which is always freezing and attracts condensation and eventually gets a bit mouldy. The paint hasn't dried and is now dripping down. What Should we do? Sand the drips and then dry it somehow? Would you use a dehumidifier or a hair dryer to dry it and try again? Or just not bother painting again.
Selling in two weeks and worried buyers will have something to say

Get an electric heater of some sort near to the base of the wall. Not sure a hairdryer is going to be enough tbh, possibly a fan heater with a decent wattage as it’ll circulate the air to an extent too. I think a heater rather than a dehumidifier will work better as it’s probably the fact the wall is cold that’s causing the paint to stay wet.

Edit to add, I have one of these to heat my conservatory, would probably do the trick

www.screwfix.com/p/2kw-electric-portable-ptc-heater-red/9158t

We used a dehumidifier.