Charlotte,
I hear you and I know you must feel so frustrated. There is a big opportunity to make a change here. But it isn't easy. I totally get how hard it is to run a business and keeping our customers is so very important! It's not a luxury economy and there is much risk to be had.
At the same time, I think it's worth the risk to use this specific client as practice. I clearly don't know exactly how she is, as I am not there. But, from what you are sharing, it sounds like she is much like the three year old who pushes those boundaries. We can all relate to this. She tries something out on you, maybe a bit of cheek or being late and then telling you not to rush...this is a moment for you. She is tipping her little toes over the line and looking at you to see what you will do. If you do nothing, those toes will go further next time.
She may not be a bad person and you are not a pushover. It's just human nature sometimes. But this is your business and you seem to have a great deal of integrity. Part of growing your business and strengthening your integrity is to grab these moments and get your foot in the door. You can do it with kindness and respect, but it still will require a certain amount of honesty.
One of my fav things to do is play "Best and worst case scenario". What's the absolute worst that can happen if you tell her that being late is not longer OK and that you will not be selling her hair to go elsewhere. You are happy to do her hair and really appreciate her business but just cannot go along with not feeling valued. Same as she would want.
The worst that will happen is she will leave in a huff and never come back. Maybe she will even talk about you in a negative way. However, I seriously doubt anyone who is your customer is going to believe anything negative about you.
What's the best that can happen? You can teach her that it's not OK to treat others the way she is treating you. And believe it or not, that is the compassionate thing to do! You can come away knowing your boundaries and feeling very good about yourself!
OK, so now I sound like I am blathering along. But really, you are doing a great job and you deserve to be treated with respect!
Thank you all so much, these are very true! I'm going to have to get harder with her... She tries it on at every opportunity even asking for a higher discount as she's a 'porper'!! She said earlier "well I'll just buy the hair off you and have them done else where then..... " she said it Really arsey..... Then had the cheek to say "you won't rush my extensions now will you" grrrrrrrr!