Hey @Polar24, Alex here.
That's certainly quite odd, you should be able to get the price that you originally agreed to. We have the history for all of our prices, so we'll be able to verify the time of your order and see what the price was at the time. If it was $10 per month, there should be no issues with correcting the financing promotional credit.
Get in touch with our customer service through any of our channels here and we'll make sure to correct this issue.