PSA is a great company: great quality components with great prices. But they've been swamped for the last few months and having trouble keeping up. I'd be patient with them, you will be happy with what you get for your money. And maybe they're slower handling emails than phone calls.
If you ordered a rifle or complete upper maybe one component is back ordered. Sorry to say but as you buy more ARs you find OOS and delays are commonplace because of demand.