goods payed in full, no delivery for two weeks

Please assist with a query: We bought roofing material from build-it Dennilton, on 6/02/2021. We were promised delivery for the 11th, until today we are still waiting for material that is well over 100k. We called the store and we were advised that they do not have stock, which was last week. 1. Why accept purchace for goods if you know you do not have stock? 2. Isn’t this supposed to be checked on the system in order to advise the client before payment? 3. Were we not supposed to get that information on the same day we made the purchase? This is unacceptable as it is delaying construction. We just want a straight answer as to how we should proceed. As we have been waiting for feedback until now…..or Please process a refund if you cannot fulfil the order To top it all of, there was a cashier who was very rude, like I was getting the stuff for free