Evening all!

My niece owns a 1.4 Golf and is currently having a problem with her heater. She said it would only work on setting 1,2,3 and not 4 but then it changed and would only work on 4 but now it has gone completley dead and does not work at all.
I've phoned Volkswagen and they told me they "have not come across this problem before" which i fail to believe but i'm just a bit concerned as Winter is fast approaching and don't want her to get stuck without any heaters available.

I've been doing a bit of Googling and have come up with a possible Heater ballast resistor fault? I don't have a clue what that is but i'm just throwing it out there.

Any help is GREATLY appriciated! Thanks for your time people