Join Date: Oct 2007
My Motorhome: Swift Kontiki 615
Thanked 810 Times in 725 Posts
All tags are the same and simply identify a person's bank account and authority to debit. Vehicles are measured in the entrance and charged accordingly. If eg your satellite dish takes you over it will charge more. Pressing the buttons and announcing; "Je suis camping car classe deluxe" MAY get you a reduction, or a burst of laughter.
Ours has always been correct.
If it is not working reliably, the most common faults as you said are;
a. Not having it where the sensor can scan - we have an overcab bed and it cannot scan the tag there, so our tag is now where the old UK VED used to be displayed, it works superbly there,
b. Not approaching the barrier closely enough, or going too fast, the ping only comes when the bonnet is about 75 cm from the gate from our experience with both the car and the MH and yes, we often use the "30 kph" lane and have never had a probl.
Hope that helps, feel free to quote my post, copy and paste where needed.
Any typo that I make means the errorists win.
Any comments above are only MY OPINION
and should be read as that.