Unfortunately it is not possible to complete a halted order. It is not possible to redo a failed payment. Uncompleted orders will be canceled automatically after a few moments and the tickets held in the order will go back on sale right after. The best thing you can do is to try to place a new order.
Here are some suggestions that will hopefully help you successfully place a new order. You can try to place the order using a different payment method, a different browser (in our experience, Google Chrome works best) or you can try again from a different computer/IP address.
If you are ordering from outside the Netherlands, you can contact your bank to make sure that they allow international transactions. During peak sales it might not be possible to place a new order, since you will not retain your place in the queue. Reaching the ordering process does not entitle you to buy a ticket. As long as no payment has been completed, no rights can be derived from reaching this part of the process.