They should be two seperate zones with residents of one having to pay full price if they enter the other.
Skully I thought you were only charged for crossing the boundaries, so if your car remains parked (even in the zone) for days, as long as you don't cross a boundary you don't get charged... At least that was the case in the first year, I drove in on Saturday left my car in my works car park and took it home the next weekend without paying.
Lynx has it right. You were parked in a car park - off the street. They scan your reg plate when you pass the boundaries in or out, but they also drive around in vans with cameras on which can scan you and make sure you're registered as paying. If you're a resident, and you park on the street, you'd need to pay the minimal reduced yearly charge or you could, in theory, be charged for not using your car.
Lynx has it right. You were parked in a car park - off the street. They scan your reg plate when you pass the boundaries in or out, but they also drive around in vans with cameras on which can scan you and make sure you're registered as paying. If you're a resident, and you park on the street, you'd need to pay the minimal reduced yearly charge or you could, in theory, be charged for not using your car.