Is $4,000 to adjust plumbing rough-ins for basement bathroom finish a fair price?

I am finishing my basement and putting in a bathroom. A family member who owns a plumbing company did the work. Rough-ins already existed, so they just needed to adjust some lines. The initial estimate was around $3k, but the final price came back at $4500, which was a 50% increase and felt like a bait and switch. I was surprised and offended by the large increase, especially since I didn't think 50% more work was done than initially planned. I clarified that he did not install any fixtures like the toilet, shower tiling, doors, or vanity, only adjusted the rough-ins and installed the grinder pump I provided. After discussing it, he came down from $4500 to $4000. I realize now that the initial quote was likely loose and I misunderstood plumber rates. There was no formal proposal or written documentation, which was probably the root of the problem.