I'm less than impressed with a company that asks for more money after the sale has been completed due to a 'System issue'. As others have said, when I bought mine the page was showing a consistent discount banner and the discounted price. This appears to be a personnel-based mistake or decision reversed rather than a system issue.
What's to stop banggood.com asking for yet more money after I've paid the additional amount?
This is only my 2nd purchase from them, and if this continues it'll be my last. I know they're a low-margin operator, but bad calls like this one can be a lot more costly reputation-wise in the long run, especially in a busy forum like this one.