I couldn't get through to fraud yesterday although that may have been a Skype issue. But talk about complicated.
My bank says Delta ran the transaction multiple times on both my credit and debit cards and they were all authorised so this is a Delta problem. The 5th attempt raised a flag and their fraud system kicked in and started declining. Part of this is down to Delta billing each ticket separately, although some of the amounts are actually for all 3 tickets.
Today Delta said no tickets were issued as no payment was made, so they had to find all the flights again. Fortunately they were able to although it cost me 1500 points and $10 more. The agent then had problems with billing again but appeared to know more about why and said she'd get a colleague on another system to try and the payment went through OK. Except that it appeared at my bank as 3 transactions again, but each for 1/3rd of the total.
They really should resolve that - I imagine a lot of banks will decline multiple payments run through all at once, so a group of 5 would have problems with my bank for example.
So I now just have to wait to see if all of yesterday's transaction actually appear on my statement.