> IANAL But AFAIK in civilised jurisdictions if I offer a service for money, and you offer money, I must offer the service.

First off, you need to stop using the (incredibly loaded) word "civilized".

Second, I am not aware of ANY jurisdiction in which businesses are required to provide their services or products to anyone.

Third, THIS IS NOT AN "OUT OF CONTRACT CHARGE". This is a charge which IS IN THE CONTRACT.

Fourth, anti-discrimination laws have ABSOLUTELY NOTHING to do with charging someone a fee when they don't pay you in a timely manner and/or cause you to incur higher costs (such as decline fees or NSF fees).