Fuses add the possibility of a single phasing condition, so adding fuses to replace a CB should then also include the addition of a phase loss monitor down stream if there is not already something there to do that.
Bottom line, your employer must provide a safe working environment. That includes having all electrical protection equipment maintained to be in proper working order. That implies not only periodic testing, but following the manufacturer's recommendations for testing or replacement after serious faults. So they must do something, ignoring this is not an option. If testing is performed and it passes, I would not worry about forcing a presumptive replacement. But if it fails, then someone will have to evaluate the replace vs rebuild equation.
Rather than just automatically deferring to Sq. D, I would get a quote and suggestions from a NETA certified apparatus service shop in your area. Chances are, Sq. D Services is just going to take it to one anyway and mark it up to you. That's the way it works around here.