Alice and Bob live in an apartment, so it's the landlord or building supervisor's job to see to the repairs. However, he or she has been slow about it (despite being asked to get it fixed three times), so Bob decides to take matters into his own hands.
Inverted: Bob calls the plumber to fix a minor issue that he could have repaired himself.
Bob appears to have fixed the leak.
Bob decides the problem is too big and calls the plumber.
But a much worse problem has cropped up during this project.
After attempting to fix it himself and failing miserably, making the problem much worse than it originally was.