Well, first off I would recommend restarting your browser, for a fresh start. Go back to the J&H store, type your username, and select the items you want to purchase. Then, proceed to checkout, put your correct billing information, then, you will be taken to paymentwall, enter the correct Credit/Debit Card information, make sure that everything is correct, then purchase. If it says your account is locked, or if you are still having trouble, you can email info@itsjerryandharry.com, with your problem, and explanation.
Please send an email to info@itsjerryandharry.com explaining the problem you are facing, try including screenshots