"insist on payment by credit card which cannot easily be stopped"

I have dealt with such idiots by 'losing' my credit card, and having the bank issue a 'replacement'. OK, a bit of a temporary nuisance for a few days, but if they keep on trying to take the money out, technically it's a 'theft'.... :-) and then the credit card company guy in India has to deal with the ISP guy in India - probably over morning tea in the same office in India.... :-)