Thanks that what I was looking for.
Do you know where I can find the payments method ? is it on Ingenico payment page or in a link ? if yes which one.

I have also another related question :
Can I restrict a gateway to a chosen plan according to the following : ?

I would like to have a set up this way :
1) 5 annual plans with 5 annual prices (360 € to 1440 €) -> normal ingenico gateway

2) Once one of the annual plans is selected we would show a drop down field [cb_mensualisation] to choose the number of times for the payment (is it possible to display this field within the payment description ?)

3) One sub plan with one price (30 € fees) (available for all 5 main plans and price added to the main plan) allowing to choose a payment in 2,4,6 or 12 times -> manual gateway (we set up the payments with Slimpay in chosen times)

If the input of [cb_mensualisation] is anything but 1, we would like to only allow payment with the manual gateway and not the normal ingenico gateway.

I cannot figure out how to configure it this way ?

Thank you very much for your detailed answer which helped a lot.

I also figured that we could simple use a promotion to add a 5% fee to our plans if the payment is splitted in several monthly payment with our manual gateway.

That could be simpler and it seems to work except for the selection of the gateway.

We have set a drop down field for values 1,2,4,6,12. If the customer selects one, the normal gateway is used. If the customer selects one of the other values, the promotion applies with a fee of 5%

In this latter case, would it be possible to link the manual gateway to the promotion or the field ? I did not found an owner area in the two for this.

Do you have an idea if it's doable ?

I think we would prefer a promotion because it would be more convenient in the future to adapt fees to plans

Thanks in advance

Ok one last question

Configuring three gateways based on Ogone gives three different return url in the settings.
As Ogone was originally configured to use the first gateway return url and that there is no ability to set several urls in ingenico back office, will that bring problems with IPN ?

What do you think ?
(Configuration with three Ogone gateways was the only mean to get three separated methods)