Hopefully you already have a second key. As I am in UK this may not be a lot of help, but if I describe what I had to do to get an affordable key it may help. I have an A6 which had only one key, the previous owner had tried ebay but the keys did not work. I found a guy in Glasgow who came out to my vehicle and went through the following procedure. Firstly he connected to my cars processor to get the appropriate code (it also told him the car key history) then he transferred the data to his own system in his van (fitted with very expensive equipment). He then inserted my key to physically copy, and then the copied key was then programmed. The key was then tested successfully in my car. It cost me £60 for a simple key without any push buttons. If you search on the internet you may find some one doing the same function near you.