This could be one of a few things. 1st, the card on file could've expired..2nd, The debit card used didn't have enough funds and 3rd, you never saved the card on and you could have forgot to add funds. This is why having Auto-Replenishment, will keep you from lapsing.
I would call the credit card customer service and see if they have any connection problem with MDX. If they don't, go to or call MDX.
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