What service or repair would be related to timing chain/tensioner arm failure?

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Three upper chain gaskets were replaced. Two weeks later, check engine light on and the vehicle was not drivable (extremely rough idle/shaking). Towed back to dealer and all plugs and coils had to be replaced. Three months later, complete timing chain failure. Can there be any correlation between the timing chain failure and the upper chain gasket replacements or the failed plugs & coils? Should the tensioner arm for timing chain have been checked and/or adjusted in either of these repairs? All service and maintenance has been performed by the VW Dealer and all recommended service was performed, when recommended.