Add-on as drop down / select one only

[tweakservers]

Hi,

 

I have a Product A and there's few 2 add-ons type which are tied to it.

 

Those Add-ons are differences in quantity only, such as 5 Mailboxes, 10 Mailboxes(as example). I would only like user to only select one of it but not select 2 of it which makes it like a total of 15 Mailboxes, any good way to achieve this?

 

thanks,

[WHMCS John]

It's probably best to use the Quantity Configurable Option for this instead of addons.