Just used my Diners to get fuel at a Coles/Shell servo. Worked fine, but the readers are definitely not compatible with the chips yet. Tried payWave first and got a message saying the chip has not been registered. Then inserted and got a message saying chip is not activated, use swipe instead. Swipe+PIN worked fine first time.
I also asked Citibank if it's possible to stagger the billing/statement dates of the two cards (in my case Signature Visa + Diners Club) for the purpose of making them more useful in an interest free days sense. ie. if the billing date for the Visa is say 20th of the month, then can you make the Diners billing date 20-15 = 5th of the month instead and thereby have an option to maximise interest free days as much as possible. It was clear they understood what I was asking for, but the answer is no. The cards and their statement periods are inextricably linked together.
I thought it was worth asking because I do know for a fact that Citibank can change your CC billing/statement date at request. I did so once because I also have an HSBC Platinum card which inconveniently had the exact same billing date and 55 interest free days as the Citibank one, so I asked if I could move it to offset it by 15 days to the HSBC and to my utter amazement, they said yes. For the record HSBC also agreed to move the billing date too, but obviously I only needed to move one, so Citibank it was since they responded first.
It's also taking a long time for Diners transactions to appear across in the My Citi summary page of online banking in Citibank. I used mine at Coles supermarket for first time on Saturday and I still have no Diners Club card even showing up as existing at all in the My Citi summary page of online banking. Not a problem for me. In fact if they lose the transaction entirely and it never shows up at all… then bonus! But just a bit weird is all. New thing beta-testing bugs is my guess.