Diners do a very poor job announcing their promotions and a poorer job posting the points. I often have to call themn and ask for the points and the call centre rarely seem aware of any promtiopn and have to ask what when etc.
I have just been offered double points on all spend over $1500 per month from NOW (no date given) till the end of July. Very poor PR.
Pity its not quadruple points of spend with Qantas and hotels. I could be 100K points better off this month. But alas, my Diners card is of the corporate version and I only use it for company expenses so no supermarkets or service station purchases.