blue frog is right.
Calling or texting customers if you ask me is the worst thing i have ever experienced i still have a few customers that i call or text but these customers start from £30-£45 so i do it because there is access problems and they will not settle for the front.
however calling and texting gives customers the opportunity to say not this time i however make it clear to them before i clean it the first time that i am asking for a 1 year agreement, and that i am investing my time in cleaning your house now when its rotten and that keeping it clean is the part where i make money.
so basically i tell them if its a £20 house 1 clean will be £50.00 or its £20 every 8 weeks which would you like?, i make them understand that appointment window cleaning and regular window cleaning are two different things.Then if they would like to be called for access i might say ok however remind them that i am NOT ASKING YOUR PERMISSION if i text or call you the night before it means i am coming whatever happens if you cant unlock , or be in to let me clean the full house i WILL clean the front ONLY and charge accordingly
I found out that if you have a round of customers that you call each time rather then turning up it lowers your hourly rate because if you call them some may ask for times and want to be in etc before you know it your customers own your business in other words they are in charge
To sum up my advice would be to stay clear of customer contact , if you can even get paid by standing order. Just don't talk to them! unless they haven't paid in a while