Hello Nijel,
Thank you for your order!
It says on the Starter page that if you want to upgrade to Mini you just pay the difference. I can't seem to find where to do that on the website?
Yes, that is correct. Currently, we are finishing preparing a special upgrade form which will allow our customers to order upgrade keys. Meanwhile, we can simply give you a 50% discount for the MINI license.
Feel free to start a support ticket and I'll send you your coupon code. Thanks!