Nonetheless the topic itself is a good one, though Windows-Chepstow (Tosh in a previous incarnation) no longer does it.
It's relentless for one thing, and there are some months when you end out paying the customer! 
Ian's mostly right, though I do have five customers who still pay me by Standing Order and I'm getting hassled by another customer who wants me to give her a form so she can pay by Standing Order.
As for the 'paying the customer'; I clean calendar monthly mostly; so I receive one payment, normally at the beggining of the month and clean the customer's house during that month, but on occassion I've fell behind and received two payments without cleaning the customer's windows.
In that situation, I clean the customer's windows and put the cash through the customer's letter box, which feels really weird; like I'm paying them to let me clean their windows.
One customer, after I gave him the cash in his hand, told me he was putting his prices up for next month!
I haven't put these particular prices up since I set up the standing order, 'cos I thought it would be difficult to arrange the paperwork; however; Wor Little Un goes to Kumon (it's an after school maths class) and we used to pay £45 per month for it, but we received a letter saying the price had increased to £50.
I sorted that out quite easily, so my customers could too; so increasing the price isn't a problem either.
I may have another push at getting my long standing customers to pay by Standing Order again. It's really simple.