I would imagine right now you need a more appropriate response. I am unsure as to what Lemon Law is but nevertheless you seem to have some sort of contract. Read the terms and conditions of termination. If that looks like it's unfavourable to you send a letter stating your intention to terminate the contract yourself and would seek legal representation. The vehicle may be deemed, "unfit for purpose" due to the unresolved fault. State in your letter what you would be happy with as a resolve to the problem and make sure it is a fair request. Finally CC the letter to the CEO of Audi America.
Good Luck
Good Luck