I can quite believe that pipes and cables disconnected during a service are not replaced, because this is my experience with my wife's Corsa.
We have 5 Opel Corsas in the extended family , and every single one ( serviced at different Opel agencies) came back with an issue with the fuel filter problem I highlighted.
The problems are common, the causes are all negligence. Professionalism in the motor industry is on the decline if already non-existent.
No one cares anymore. One of the reasons is due to the increased use of "Extended warranty service plans".
How often have I heard people say "I don't care, that is why I pay for an extended service plan, if they screw up, they must fix it".
Well they don't fix it, they ignore what they want to when they want to.