No Laptops even though they are advertised

In April I received the monthly booklet showing your offer for a Dell laptop at R249.00 per month on contract. I have been waiting for your Pinetown branch to phone me letting me know they have stock. They told me repeatedly that they get their stock from Westville Pavillion branch. This afternoon I went to the Pavillion branch only to be told they do not have stock yet, maybe only next week. This month the deal for this laptop is R399.00. Question, am I entitled to get the laptop on last months deal as I have been waiting for a month now or do I have to pay the new price? Personally I do not see the logic in advertising items which are not in stock.The young man who helped me was most apologetic and stated it was not fair as they, the staff, get complaints from the public wanting the laptop deals.