Bathroom Tiles - Smart Repair

[chris.tarry85]

Had a new bathroom installed and noticed that three of the tiles have small chips on the corner, these were almost certainly there before installation, but frustrated that the fitter did not spot and swap for spares (we had plenty).

Really don't want to swap them out as am sure this will damage plasterboard underneath and be a nightmare, so was thinking of saying I wanted him to have them smart repaired.

There are lots of companies and videos which claim to do his, but does anyone have any first hand experience?

Picture of damage attached for reference.