Clueless sales person

I'm interested in purchasing a new Audi. Having never bought an Audi before I went to the sales centre at Audi Menlyn with great expectation. Asking the salesperson what the difference is between the different sedans in the A class, the answer is: 'they get bigger and more expensive from 1 to 5'. He didn't offer to show me the different types, to tell me more about the performance, the interior etc ... I'm sure Audi can afford to train their sales people to be more informative / enthusiastic on the product they sell! I am so disillusioned.