I had one customer (now an ex-customer ) who was on the phone when I rang the bell for the money. The front door was open.
The person on the other end obviously heard the bell over the phone and said something like "was that your doorbell?"
"Oh don't worry, its ONLY the windowcleaner" said my customer and carried on talking for another ten minutes.
It wasn't like it was an important call or anything, it was just chit chat, I know - I had to stand and listen to it.
I would have kept knocking and ringing the door while she was on the phone, got paid then got rid of her, telling her I don’t take on ignorant customers.
With that atittude Ewan you have a lot to learn, Telling people things like this will do your business no good at all, upset her and she may tell 10 people how rude you are, keep quite and she will tell none. 
I have a professional approach/attitude and I provide a professional service, I have to because I run (trying) a professional business and I deal with professionals in both my commercial work and residential.
If you don’t know how to deal with time waster and rude people you will go round in circles. The occasional customer or potential customer who I give back there own treatment, I couldn’t give monkeys about what she thinks or who she speaks to. Fact is I have as you do and everybody on this site more satisfied customer than any dissatisfied customers, so don’t worry about what these characters say to other people about you, they are very unlikely to guarantee your success. (but they can make it harder for you, just being rude that once based on feeling at the time)
I personally will be polite to these people as I do not let (try not to) let them get to me, we will all have been rude in one way or another at one point, but I now do not let them take me down to there level, I smile and walk away, being rude means you go down to the same level and that is not professional at all (even though it does feel good at the time) I always give a monkeys what they think as there freind could be the next big contract as you really never know who they know.
Ian
That rubbish Ian, you at least need a certain amount of respect (self respect) to do business with others. Without that you won’t be going anywhere.
Hoping some impolite will give you a golden lead isn’t worth it; and very unlikely to happen, unless they want to carry on degrading you.
I don’t lower myself to there level one bit, I stand up and if need be teach them a lesson, I don’t need this type of person one bit.
Fact is the higher up you go the less chance you will meet this sort as they won’t be able to function where there’s has to be civility.
That's not rubbish at all Ewan, being rude to some to make yourself feel a bigger person or just to get a poinless point across IMO it is wrong (not saying your doing it for them reasons but you should be able to see the point I am making ), it is unprofessional, I personally could not give a dam what they think of me as I am in business to make money I do not have to like them, if they offended me I would fight my corner but in a polite way, but I will not knowingly be rude to make myself feel better or to teach them anything because it does not do me any favours at all, I could be rude or what ever, I have had to teach myself to be polite in these situations because it makes good business sence to do it, I was not so understanding/ tolerant at the start I must admit.
I hope you see the point I am trying to make. I am not attacking you by the way and everyone if different, my sales approach is very different to many others but works very well for me.
