Hey Scotty I'm from New Zealand, I have a problem with my Audi A4 2.4L V6 B6 2005 Cabriolet. The car starts as normal with electricity and it's mechanical parts going, but the PRNDS is blinking and when you set it to Drive or Reverse, it feels like you're in neutral because it won't move but unlike neutral that does a huge REV this only does a very little rev. This is also a rare occurrence and not a permanent state so it happens on random the car is "AUTOMATIC"

A way while ago, I tried replacing the Knob I'm not sure if that affects anything...

The guard underneath was also damaged/scratched by a pipe sticking out of the ground sometime ago. The Mechatronics is one of the mechanic shop I went to and concluded it to have detected a problem "p1757 intermittant supply voltage open circuit came up"

The Brakes is quiet weak, and indicator lights also are faulty. 

Those are my only suspicion, I am not a mechanic but I try my best to investigate. A lot of mechanic in my area likes to rip people off, the reason why I think so is because they have different answer. One of them said $7,500 for 2nd hand transmission and $3,500 labor (20hours) 

I really need to know what truly is causing it before spending money for repair, I don't wanna service the brakes etc if the problems electrically/mechanically is unfixable

My hope is losing and I love my car it means a lot to me...