If each site has its own heat tape plugged in to that meter, why isn't that a legitimate cost to you??? It's not like they're charging you for underground pipes that need no protection from freezing. Furthermore, the heat tape not only guarantees you water, it preheats it BEFORE it gets to your water heater- if only a little.
As far as "forbidding them to charge your credit card": say what??? The credit card is their SECURITY DEPOSIT against nonsense like this. When you gave them the number, you authorized the use....withholding here is no different than if you'd stopped paying site rent before vacating.
