If it was a simple recement crown I’d normally just stick it on again and not charge the patient, doesn’t take much time to do and worth it to retain goodwill.
Probably isn’t though as I’d have done that when she came in, if she needs another appointment it may be that the tooth is broken below and it needs posts placed or a core built up again.
Should ask why it failed, what needs fixed and what you are paying for.
If it was a back tooth root treatment and crown for several hundred quid was it NHS or private, if only 200 quid probably NHS and to be honest its not really profitable to do….
These problems arise because of poor communication, either dentist doesn’t tell patient or patient doesn’t listen then they end up complaining about the cost