Trafic 2.dci 115 Oil pump chain

[Tim06]

Hi guys,(and Girls!),
I'm trying to help a friend with his Trafic 2.0dci 115 which has suffered a timing chain failure. On opening up the timing cover, aside from the obvious problem with the timing chain and sprockets, there appears to be a
large amount of play in what I believe is the oil pumpdrive chain. There is no sign of any tensioner on this small chain, but there is a 20mm difference between holding the two sides of the chain together or apart. We need to know how this chain is tensioned and, if it is worn, how to change it. It appears that the engine would need to be removed to do this!
That's one subject and questions, now the other with regard to the timing chain issue.....
The van died whilst being driven. It will turn over, but sounds to me as though there is a "tight spot" on rotation. Inspection of the timing chain and sprockets shows severe wear, with the tensioner almost completely extended.
This leads me to believe that the timing has slipped with the possibility of bent valves broken, rockers or worse! I've searched on line and have found various answers saying that if lucky it will be broken rockers, others that say bent valves, broken camshaft etc! Even removing the cam cover appears to be very complicated and then might not show all the damage!
any advice on how to proceed would help enormously!
Due to the age of the van (2011) a recon engine is far too dear and a second hand one appears to be rather a risk unless the timing chain was replaced prior to fitting it!
These engines seem to be rather susceptible to this failure!!!
All suggestions and info gratefully received!!
Cheers, Tim.