If the cam chain tensioner is known to fail I wonder why SEAT didn't send an advisory letter to you to take the car in for the part to be replaced. I owned a Toyota in the past and I received two letters advising me to take the car in for work to be carried out, free of charge.
Apparently the cam chain tensioner failing is a known issue with the ccz engines in early 2009. Really pathetic response from SEAT UK.
If I sell my car I doubt I'll buy another SEAT or VAG car, especially if this is the type of response you're going to get.