Purchase Users at a different discount without Tiered Pricing
We have a customer who purchased 1500 users at a 66% discount on an annual evergreen subscription, paid up front (and we received payment). Its been several months, and they need to add 200 more users...but the order form we have in place for them specifies that they have to purchase users in blocks of 500 (not typical for us) and at a different discount (68% instead of 66%). We do not have tiered pricing in place, and I was wondering if supporting this was possible? They paid for those original 1500 users at a specific price, and we don't want to touch that...but we want to add 200 users at a different price point without having to do an amendment that will REMOVE the original 1500 users and apply the payment to the NEW invoice of 1700 users (at a different discount).
Any ideas? Just a new invoice at a different price point without having tiered pricing in place, is what we're looking for.