I have had the same issue but for the Samsung A52 5G. When placing the order i was told to choose a specific delivery date which I chose for 2 days time aka today. I hadn't received a dispatch email and so phoned only to find out the item is out of stock and won't be in their warehouse until next week! Very frustrating as I specifically chose a different colour phone to my favourite because that one was said to be in stock. If I had to wait anyway then tell me all the phones are out of stock and don't give me the choice of a delivery date! Very very annoyed.
Did you eventually get the phone and if so how much later was it?
I have thew same issue. Bought the phone on 21/06, earliest date for delivery was 01/07 so I picked that. 01/07 is now nearly over and no word of dispatch, let alone delivery. Been onto the "Support" people several times and they just can't/won't help me. Granted I was getting a bit irate with them but that was on the third phone call. They seemingly can't check why it hasn't been dispatched, can't give me a new delivery date or any kind of estimate as to how long it will be before it can be sent and to top it all I can't cancel the order as it is is shown as "preparing dispatch", which it went to the day after I ordered it. It seems they have done this to prevent me changing or cancelling the order. Absolutely awful service and I hate to say it but I've never had anything but good service from fruit-based phone makers.
I'm currently trying to get the phone to me at some point, first they said my phone will still arrive today 7pm without any correspondence from DPD or any emails saying my phones been dispatched. I'm absolutely furious, the second person on the phone said she'll chase it up for me and I recieved no correspondence from her. The third lady, after me having a rant on the phone said there's an option for me to wait for the product with no promises. Currently waiting to be transferred to a manager. I've waited 15 days since the day of my purchase, its ridiculous. And they're now trying to offer me alternative models? Which are no where near the same price point. They should've never made the s21 ultra available for order if they could not deliver. I'm waiting on this phone to come through the door so I can leave the country, and now I'm having to forward my flight date. There should be more compensation then just the phone at a later date, some kind of Samsung credit or something becauses this has just been an disgusting experience. So disappointing seen as ive ordered from the site each time I've bought a new phone.