TBH, after a conversation I had with an indie specialist today I'm thinking of pulling out if it's possible and won't affect my credit rating.
Basically, if what he said is true, changing to the later tensioner and chains won't necessarily cure the issue as they're not sure it's the tensioner, but chain stretch.
I asked him if he though changing to the revised chains would cure and he still wasn't optimistic and said that only the later engine revision around 2012 was the certain thing.
Not sure if this is true, or just speculation, but he said there were theories about what causes it, one being load on the chains with people parking cars facing uphill with handbrakes on but the car in gear.
From a lifetime of being round cars it sounded a little far fetched to me, but the more I get into this I feel I might be better off pulling out if I can and just finding a different vehicle.