Check the outcome before repeating your purchase.
If checkout stops unexpectedly, first look for an order confirmation and check the payment status with your payment provider.
A practical next step
Record the time, the method used and any error message, without including sensitive card details. Contact the team if you cannot tell whether an order exists. A pending transaction and a completed purchase are not always the same thing, so explain exactly what you can see before attempting another payment or placing a duplicate order.