You don't say what mileage in on the car.
Timing chain stretch is normal wear and tear and worsens if the car has lead a hard life. My wife's VW Jetta suffered a similar fate with bent valves at 55k miles and a new engine was £6k. If my car ever reaches that mileage, I'm having the chain and tensioner replaced at 60,000 miles as Audi overestimate the life of these parts.
Now: 2011 A5 Sportback 2.0TFSi quattro SE, S-Tronic, Ice Silver + Cardamom Beige/Black
Mods: 7-digit postcode (by Hazzydayz), Ventureshield, LED interior lights + reversing lights by T8ups
Prev: A8 4.0Tdi quattro
Prev: A8 3.7 quattro
(The Beemer is a Bike)