Hi I can't help you with Bunbury, but I can tell you if they felt there was any risk of doing the op regionally they would refer you to a major centre.. i had an ENT decline to take my DD's T and A's out as he felt she was too great a risk for the hospital he worked at, (she had other health issues as well) and he felt that she should not have it done unless at a hosp with PICU facilities (pead intensive care) He then referred us on to a great ENT who worked out of Melbourne's RCH and who did eventaully do the op but only after a long hail of getting her fit and well enough to operate.. The op BTW went swimmingly with no issue..
What are your mums fears, is it the fact that it is regional, your childs current health, what would happen if there were complications?? Perhaps she could attend a Dr's visit with you to discuss them as well.
In our case we did have concerns about my DD's medical history, her current state of health and the fact she was so very ill prior to surgery. It took a further 2 months of A/B's and constant monitoring for the Dr to have her at a place where he was happy to do the op....