Customer Class Assignment Priority

When a customer is signing up, Billing assigns him or her the customer class based on (in order of priority starting from highest to lowest):

1. Payment method used by the user on check out (this can be set by the Auto-assign Customer Class option in payment method details).
2. Promo code specified by the user (this can be set in details of the respective customer class).
3. Service plan in the basket (can be set in the details of the respective service plan). If multiple plans are put into the basket, the first plan (the one that was added to the basket) defines customer class.