Another heater problem

[steveselvage]

I have a 2000 tipper mk5 td and the heater blower has never worked in the month i have had it, after getting soaked while working yesterday and driving home freezing i thought id have a go at sorting it.
I found that the 30 amp fuse is intact so i removed the centre of the dash and found that the wiring has been butchered.
The fan switch has had the earth wire cut and a new bit put in that goes to an earth point inside passenger footwell,the supply has been cut and a feed has been piggy backed from the ciggy lighter,which also dont work.
I checked the fuse for the cig lighter and a 30 amp one has been fitted and burnt a hole in the fusecarrier,obviously too much current from that fuse position.
Im afraid i dont know a thing about auto electrics so i would like some advice about what to test and in what order.
Why do you think the supply was re routed,do i need a switch?resistor? auto electrician?

[AndyG]

It's possible the fan is seizing up and drawing too much current Then some bright (or not so, as the case obviously is) spark, decided to run the fan off the ciggy circuit, of which obviously isn't up to the job

Best thing to do is to try and get the fan to run off the original circuit, but sounds as though soldering and heat shrink will be required and that's if the fan is ok