How to purchase stuff that is either not in stock or does not get delivered

I placed three orders with OneCart, as follows: 1. Batteries from Woolworths that were delivered; 2. Sparking water from Pick 'n Pay that was out of stock and for which I was refunded; 3. Canned sweetcorn from Makro and sparking water from Pick 'n Pay. The sparkling water was again out of stock and I was refunded. After pointing out a few days later that they did not deliver the sweetcorn they made up a story that we were not home when they tried to deliver, when their own system showed that it was outstanding. They then said they would deliver the sweetcorn, but they did not. Upon inquiry I was informed that it had been refunded.

What pathetic service