Perhaps if there is a middle system the DR banks might be having communication problems with that system more than usual.....
Talk about the DR banks and the international systems (VISA/Plus and Mastercard/Cirrus). The local credit card processing network (CardNet) cannot even release the authorization hold from the debit cards, even if they are VISA cards (but debit), not sure about international debit cards.
Why? Because the "authorization" is immediately applied as a charge, and even if they release the authorization, the money is not returned to the account.
Happened to me with a Banco Leon debit VISA. My authorization hold (over 12.000 pesos) was released by the merchant (car rental) I was given the cancellation voucher. But the money did not get back to the account (as usually happens in the USA or Europe). So neither I (debit applied to my account) nor merchant (debit applied to his account) had money. The money was "in the air" (or better yet, "in the wires"). It took a letter form the merchant, addressed to my bank, confirming they released the authorization hold, a copy of the cancellation voucher, several phone calls to the bank, and 7 days to get my money credited back to my account.
So talk about the "perfection" of DR banks with international systems (VISA/Mastercard).
This also serves as a warning: Beware of using debit cards (at least DR debit cards) at establishments that need to "authorize" your card or have it as "guarantee" (hotels, car rentals, travel agents, etc.).