If you have set up a ltd co, then your VAT no. is not your rsi no. I had to wait about 4 weeks for company VAT no., eventually got it by calling them up and explaining to the lady that I needed it in a rush to process an order from UK (because when you are vat registered and buy from UK, they will not charge you the 17.5% uk vat if you furnish them with your irish vat no.). she put me on hold and then told me to get a pen! got the impression they can do it quickly if needs be, but be pleasant and friendly!