Audi A5 Registered incorrectly causing me havoc

I bought an Audi A5 Cabriolet in 2012, of which I had to pay to Audi administration fees that includes the registration of the vehicle. I was pulled over by cops in 2014 citing that the car was registered with an incorrect colour and I was issued a fine and the car was taken off the road. The car was required to go for the road worthy assessment - I had to put new tyres (items I had not budgeted for), and the car came back with the new licence disk. In 2015 November when I wanted to renew the disc; I was informed at the Post Office that the car is blocked on the system because of counterfeit documents. I can renew the disc of all vehicles in my name because of this Audi incident. I have been driving with permit for 3 months now. The car has been taken for the road worthy assessment again this January (and I had to buy new tyres again). I am fed up with this 2 year inconvenience and I am not getting clear answers as to why is this happening again. When I but a vehicle I need a peace of mind...but this is causing me too much havoc!