Audi A4 3.2 Quattro s-line cabriolet Timing Chain Noise

Hi folks. I have a 2006 Audi A4 3.2 Quattro s-line cabriolet. After a recent 52,000 mile service I was told that my car needs a new timing chain (slight rattle on start-up) and was then given a price by the Audi dealer of £3,200.
The car was three weeks past 5 years old with 52,000 miles and a full Audi service history. I have a few questions which I hope someone will be able to help me with.

Have I been quoted a fair price?
Should the chain be replaced by Audi free of charge (or heavily discounted)?
Is the chain at the front or back of the engine?
Is it a much cheaper job just changing the tensioners?
If I go ahead and have the work done how long should the warranty be on the new chain?

Any held would be fantastic, thanks so much.....

You can only hear the rattle now and then for a few seconds. I don't think the chain is worn or stretched as they tell me my engine is running fantastic! I asked about them just changing the tensioners but they are now saying they have to remove the chains to get to the tensioners anyway? To be honest, the whole thing has spoilt the way I feel about Audi cars and the way they are maintained!! Gutted...