Seriously, this is is the first time I heard in sg, anyone can be barred from getting treatment from any health care institution.
Eg even after I leeported a incident and lodged an official complaint of a loctor, this loctor will still need to treat me if in any case, I'm being assigned to his care.
IMHO this kind of thing I doubt spf can do anything or will do anything, unless when there are physical attacks.
For verbal disagreements and commotions, the only way is to reach out to the highest level of that institution, through the patient feedback service.
And your friend has to calm down and act objectively, in order for the complaint to be handled more fairly.
I know Easy for me to say, but there was once when I even needed to complain to the complaint leepartment of moh to complain to them that the complaint leepartment of that institution ignored my complaint.