Starting a dispute on Ebay.?

So I bought an item on Ebay. The seller offered free 24hr delivery and the item should have arrived within 48hrs after payment received. Paid the monday night and still haven't received anything one week after payment! First the seller said hee used APC and then no, he used Royal mail. He said he sent it royal mail signed for, but I'm not sure if that's a 24hr service. It was very hard to get him to reply and I've asked for the tracking number, but he only sent me a payment receipt from the post office. It's only the receipt and it does not state what service was used, tracking no or the postcode it was sent to. He does not want to give me the tracking no and I've asked repeatedly cause I'm waiting in the house like a pleb. Should I leave neg feedback and then start a dispute or just start the dispute? He lied to me about the service used and I bought this one solely due to it being 24hr delivery!