No customer service

Payment was supposed to go off, didn't. Tried to pay manually, says my card is blocked. I've called, emailed and chatted but no luck, can't seem to get hold of anybody. It says my card is blocked, but all debits went off ; the bank reassured me the error is from Payjustnow. Now there is interest on the payment, I didn't know where to pay so I can delete this nonsense. If anyone can assist me please help. The store where purchase was made is also not sure on how to go about this..