Wynne,
You don't understand the technique.
You're giving away ' a packet of tabs' as you put it but have got nothing in return, expect the certainty that you will always have to give that customer a 'packet of tabs' for nothing every time you go because you have now taught them that they can get something for nothing from you. And if you just meekly say, 'Oh, ok, I'll do it for £x,' then they immediately think you were over-charging them in the first place. You can then end up with them saying, 'Ok, leave it with me, I'll call you.' They then call back and say , XYZ cleaners said they'll do it for £x's, will you match it?'
Far simpler to tie any reduction in price to something the customer has to give you in return in order to get the discounted price.
Simon
Simon