Charged and cancelled

We booked a flight with Travelstart, they have charged us more than half the amount. Emails us to tell us that we need to pay the rest. I responded asking what the problem was and how we can pay the rest since the full amount should have been deducted, no response yet I get a new email saying our booking was cancelled. I emailed asking how it can be cancelled if we have paid. Still no response from either email.