Pay to upgrade membership

[pharmacist]

I want to Added a payment method for my forum to let users pay to upgrade their membership to access some private forums
but i want an automatic method to do such that
So, how to make that
2nd , What best merchant can hold the process? " Anything except paypal"

Thanks

[HMBeaty]

Just create a paid subscription (http://www.vbulletin.com/docs/html/subscriptions) that promotes users to that usergroup upon purchasing

[pharmacist]

Thanks
But I don't understand this note

If you run vBulletin with any sort of HTTP authentication system then the callback by the online processors will be subject to the same conditions and the subscription will not go through.