From a website called Justanswer.com:
"Hiya,
You'll have done some of this already but it's worthwhile doing it all again.
Unplug the appliance.
Take the condenser out.
Clean out the condenser thoroughly.
Clean out the ducting too.
Reach right in as far as you can and take out the build up of wet fluff.
At the bottom rear of the appliance is a bulged container.
Pry this open, it hinges outward.
Take the hoses off and blow up them to ensure they are clean and clear.
Take the pump out of the container and clean out any debris in it.
Clean out the pump reservoir.
Ensure the hole to drain the water into the reservoir is clean and clear.
Reassemble the appliance and try again.
When you start it up, you should be able to hear the pump running"
Of course, she may be doing all this already, but worth a go if not.