If their appointment already fully booked of course they have to prioritise their appointment customers.. and if they really not having enough technician to entertain your case and can't confirm to have time for your car of course they will ask u to come on another day or schedule an appointment on another day.. but if it's something serious i agree they have to look into your case asap.. anyway i understand may be the way they convey their message inappropriate and let u felt not being appreciated as their customers.. may be their communication skill need to be polished a bit more.. cheers bro!