After MBNA ceased its dual American Express and Visa cards for earning Miles & More (Lufthansa airmiles) in July 2018, Affiniture (which runs the UK franchise for Diners Club) started issuing dual Diners Club and MasterCard cards for earning Miles & More in October 2018. Because Affiniture (Diners Club) can’t directly issue MasterCards, the MasterCard is issued on Affiniture’s behalf by Cornèrcard UK. The MasterCard is officially a prepaid card, but is attached to the Affiniture charge card account (whose balance must be repaid in full every month).
Curve lists the prepaid cards that it supports as being “Osper, Monzo, N26, Revolut, Tide, Monese, Loot and Qonto”. So the Cornèrcard MasterCard cannot be added to Curve.
Affiniture explains the reason for the MasterCard being officially prepaid in its FAQ by saying:
My Mastercard says pre-paid on it, do I have to add funds before I can use it?
No. The card works in the same way as your Diners Club Charge Card with all charges and credits appearing on your monthly statement. The card is automatically “loaded” with cash from your account for every transaction you make. You don’t have to do anything, nor do you have to have a credit balance on your Mastercard.
Given that this MasterCard, with card numbers starting 5271 94, is not really a prepaid card, please could Curve add it to the list of supported prepaid card issuers?