Disgusting that your management gives you no support in relation to this kind of crap ditzy, in a previous job in retail where we too were times treated like crap by the public, if we were ever abused by the public and we called a manager this manager always had a go at the person by saying well whilst I do see your point that gives you no excuse to swear at my staff, if we had the public swear on the phone we told them to cut it out or we would hang up, and if they called to complain that we hung up the person was told it's policy if you swear at the staff......they were at times bastards to work for but never stood for us taking too much crap from the public.
Your management is just being weak, our management at least understood that some people it's not worth having their business, and to let them go to annoy the opposition