Hi
If you go to the Sanef website you will find that if your vehicle is over 3500kg the Sanef transponder is not useable. I copied the below-

As long as your vehicle is lower than 3 metres and less than 3.5 tonnes GVW you can use any non height restricted lane that has the Liber-t symbol illuminated. A vehicle of this size falls into the Class 2 fee structure. If your vehicle is larger than this then please contact our sister company Eurotoll.

AND

Vehicles NOT Eligible for the Liber-t Télépéage Scheme
Vehicle Class Vehicle Type Description
3 Class 3 Vehicles HGV or bus with two axles

Vehicle with overall height of 3 metres or more
Vehicle with GVW* of more than 3.5 tonnes

We have used the transponder for a few years and it makes toll routes so much easier to use. Hope you can get help from Eurotoll

Barry

According to the classification you should be class 3 over 3.5 tonnes.
autoroutes france rates
beaten to it by MR2

Hi Ozzy

We are over 3500kg as well. I did look at Sanef but you have to declare that you are under the limits as stated by the others.

Personally I haven't bothered to do anything and I just pay at the toll barrier. Nine times out of ten you just tell them you are class 2 if the auto machine clocks you differently. Paying class 3 tolls will soon make your journey an expensive one.

In our case 4500kg over six wheels is doing less damage to the road than 3500kg over four wheels.

But that's just me justifying to myself as to why I shouldn't pay more.

Spinner:(

Hi Ozzy
Before we had the sanef on occasion s we were asked for class3 rate but used intercom to get it changed, With the dome on roof I'm over 3m but that should not count but the camera doesn't know that!! Spinner has the right idea!!
Barry

Hi Spinner, so you got tag axle and 4500kg, and just drive up and get through tolls ok, will give it a go, as this will be my first time over the water, thanks again for you info.
Ozzy1955

Hi Ozzy

Yes that is correct. As MR2 has said, you do have to press the intercom button and say in your best French camping car Class 2 not class 3 or 4 S'il vous plait as it is the height that will register you at 3 or 4 not the weight.

We have on rare occasions had to pay class 4 but then got it back at the next toll station where there was an office.

To be honest I don't think some of them know what is the correct toll although it is pretty clear on the website and published docs.

Spinner