That's what I did. Cost me more but knew it would never show up. Then I read today theses amazon drivers are on less than minimum wage and work illegal hours, not surprised it never came. Amazon prime has gone so down hill since they stopped using dpd, was always going to happen.
Could be a mixup with actual PS4 stock tbh in their warehouse or whatever.
I'm on prime since it came out and I'm ordering items consistently throughout the year and it's the best service I've used. Even two days ago I've ordered Diablo 3 for the PS4 and adapters for speakers, both ordered on Wednesday evening around 7pm and were with me Thursday morning 9AM. It's always been the same without a slightest hiccup.
Maybe I'm just lucky or this could be area specific (I'm in Cambridge) but I must have ordered at least few hundred items on Prime over the last years and not had a single problem. The refund/exchange is also excellent, anytime there would be a problem with an item I just print off return label, drop it off at post office and 5 minutes later refund is on my account.
When my £300 earphones developed a fault last year, I spoke to a guy on a chat, day before Christmas day in the evening and within 2minutes he had sent me a new pair with special delivery next day guaranteed without even asking to send the old pair back.