Pandora - you have all my sympathies - I have been where you are myself and know exactly how you feel.
As has been said before the people who are tasked with crewing/rostering have a specific task to do but it is also a job which can require tactful handling. Your comments point to a lack of training and selection with respect to ground staff. It is not their fault but that of the company management that they have not had "people" training.
My advice is go and talk to your fleet manager and tell him how you feel - he/she may not be able to change much but at least you have communicated your feelings. As has been said before do not "shoot the messenger" because they are only doing their best.
With one company I worked for, which shall remain nameless, I told the Chief Pilot that I no longer felt like a "Captain" anymore because of the appalling lack of people management in the company. Unless you communicate your views nobody gets to know and, yes, one person can make a difference.
My final advice is to consider going on an assertive training course. I did and it gave me a lot of useful ways of handling these sorts of challenges! Well worth the money!
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