I agree, tiptronic is auto and the fact you can hear the stater clicking means not enough power to the solenoid or a short in the wiring like a bad ground to the starter motor

 

check your ignition switch too man. mine's gone bad twice and it made the same noises.

 

Bad solenoid if you tried to jump start it

 

If it sounds normal when you turn the key, (except for starting) I would probley say its the camshaft position sensor. I had that problem about 5 monthes ago and from what i hear they are a somewhat common. If it doesnt sound normal than its definetly your starter.

 

or if no sound the switch