Fractured (separated) pin on the cambelt tensioner

[NarrativePsych]

Greetings, everyone.

I own two 2007 A6 C6 2.0 TDi Avants, one of which I use as my primary vehicle. It has accumulated 125,000 miles and is visibly damaged with several dents and signs of wear and tear.
I purchased the second one at a very low cost in late 2023 due to a malfunctioning engine. The vehicle is in excellent cosmetic condition, with a mileage of 101000 and a valid MOT for 10 months. Despite paying £2700, which was more than the first quotation, I believed it was a worthwhile investment considering the car's potential longevity. A rocker was damaged, therefore it was replaced along with a new cambelt and cylinder head/gaskets.
Regrettably, the automobile had a catastrophic breakdown after covering just a few kilometres. I have been informed that the cause of this failure is the shearing off of the cambelt tensioner pin.
I am facing a dilemma - how severe may this situation be; is it probable that the engine would be deemed irreparable? Is it worthwhile to allocate further resources towards conducting further investigations in order to ascertain the full extent of the damage? If my automobile is beyond repair, would it be advisable to replace the engine with the one from my other vehicle, which may not be in good cosmetic condition? If so, what would be the estimated expenses involved? Both vehicles are equipped with the engine code BRE. However, the dysfunctional automobile is equipped with a continuously variable gearbox (CVT) whereas my everyday car has a manual gearbox.
I would much appreciate any help or cost-effective solutions that anybody is able to provide. I would be interested in repairing the non-functional vehicle, but unfortunately, I do not own an unlimited amount of funds.

[NarrativePsych]

[NarrativePsych]

[Micobe]

The bolt has fractured due to excessive tightening of the nut.

[NarrativePsych]

Thank you for that, Micobe. This situation has the potential to create a significant level of discomfort, considering the fact that it was my neighbour, who happens to operate a garage/workshop, who completed all the tasks on my behalf. I have complete trust in your statement, John, and I am willing to accept it. However, if there is another individual who can provide a corroborating viewpoint, it would be advantageous for me to contact my neighbour. This would allow me to demonstrate to him that there is a consensus among experts indicating that he has made a mistake.

[Micobe]

I have personally fixed 6 heads due to this cause, and it is more prevalent than one would expect. Additionally, it is worth noting that the replacement timing belt kits include two fresh bolts: one for the tensioner and another for the idler wheel.

I suppose that they were also left unaltered.

[NarrativePsych]

Regarding the repair, what would be the further course of action and how much manpower would it require? Am I justified in expressing to my neighbour that I believe he is responsible for the issue and that I strongly want him to rectify it, considering that I have already remunerated him with £2744 for the work done, which has just exacerbated the problem?

[Micobe]

What is the quantity?

The removal of the skull is necessary, followed by a thorough stripping to assess the extent of the injury. Typically, they cause deformation in the valves and harm the rollers, perhaps affecting the cam as well.

Unless the skull is removed and examined, it is advisable to anticipate the worst. Apologies if my statement seems blunt, but it has the potential to inflict significant harm, resulting in substantial expenses.