Total engine damage C4 Pure Tech 130 at 76,000 km, year 2015

Hello to everyone, I’ve been C4 driver with the Pure Tech 130 engine since 2016. The vehicle is year 2015 and was bought by me at a PSA branch as a used car. Until 2 months ago I was very pleased with the vehicle, especially I was enthusiastic about the engine. Meanwhile the car has 76,000 km on the speedometer. The enthusiasm is now gone. A month ago the engine on the highway fell into the already operation and at the same time the brake power amplifier failed, so a e highly dangerous situation. The workshop diagnosed a “dissolving of the timing belt”. The rubber particles had spread in the engine oil and also blocked the sieve of the high pressure pump, which led to the failure of the braking force. The damage was repaired and a bulwark application was made, but which is not yet approved. After the repair I drove still about 4000 km and noticed a high oil consumption, which I also reported to the workshop. This suggested to me an accurate documentation of the consumption I did not come to this point, because today the car stopped on the motorway again, only ran on a cylinder and from the exhaust came recognisably burnt oil. The workshop now proposes to me an replacement of the engine for 6300 €. Kulanz offers it in the amount of 25%, which is not yet certain. I know that this is not a new car and that the guarantee expired a year ago. Nevertheless, I think that it is an unding that a car with 76000 km has an engine-total damage. What do you mean? Greetings Raimund