Had some crazy quotes to get this tensioner replaced. One main dealer was over £2k and insisted that the chain and guides had to be replaced too as they had been revised. Another main dealer was £940. Cheapest so far was £600 from an independent VAG specialist. I've also read on some VRS forums that some owners notice a couple of seconds of start-up chatter from the engine / chain in the weeks / months before it finally gives out, this doesn't seem to be a consistent observation, though.