I think somewere you can send a solictor's letter all offical asking them to pay in 7days or we will take you to court etc. Think it was something around £2.00 for the letter the idea scares them so they pay.search on google for debt collectors or something might come up
Just do one more clean for them. Make sure you use the dirtiest, soapy water you can get.It might not be you that gets paid but someone will have to do them. Bit of aggro flushing your pipes through but, oh the satisfaction.
Already did that, they didn't pay up. Found the letter on here a long time ago actually
are you saying these people owe you £27.