Imagine if your doctor or mechanic is working on something - and it's WORSE. And he gives you these kinds of excuses. You know what you'd do? You'd FIRE him.
Actually that mindset is prevalent in those and many other positions too.
Noticed it with a family members former doctor some years back.
Fortunately I don't have that issue with my GP.
Mechanic: "Well we replaced the sensor that the scanner said to replace. Thats a new problem, even though the symptom is exactly the same."