"Audiology appointment for hearing aid part"

I am struggling to understand why my elderly mother requires a clinic appointment in order for her to have replacement parts for her hearing aid posted out to her. 

I have been informed that even although she will not actually visit the department, a clinic appointment is necessary.  Due to this, she will have to wait about 3 weeks for the parts.  This means that she is unable to use her hearing aid for this period and is unable to hear. 

I have investigated ordering the parts privately, but since one of the parts is tiny and actually has to be inside the ear, I am anxious that I do not order the right part, it doesn't fit properly and comes off inside her ear.  This has happened before and resulted in a visit to Accident & Emergency to retrieve the part.

I am a healthcare worker myself in an acute area in a hospital in NHS Tayside and, as such, I feel that I fully understand the difficulties and backlog that Covid 19 has caused.  However, I can't see that this practice is helping the situation in any way.  Surely this is likely to cause an even longer wait for those who require clinic appointments and an ever longer backlog.

I would like to know how long the clinic appointment that we have been allocated is for.  In my mind there is comparison with obtaining these parts and getting a repeat prescription from a GP, I don't actually need an appointment with my GP to get a repeat prescription.  I do recognise that someone in the audiology dept would probably have to go to a drawer to get the parts, put them in an envelope and address the envelope, but even then, 3 weeks seems like a long time to wait.

It is painful watching the difficulties and social isolation that my mother is facing without her hearing aid, but I am hoping that I can be provided with an explanation that can help me understand why this is necessary.