Rude owner

Products are wrongly priced on online shop and customer needs to pay the correct price that is much more than advertised. I have ordered yarn online, Saturday the owner Yunis called me to say one of the staff made a mistake with the prices, what does he need to do? I told him to honor the advertised price and send me the goods. He said he will see what he can do. On Monday I called him to hear what is going on with my order, he then rep**** he will work something out and come back to me. He then came back with a large amount that is the correct amount with the correct price as it should have been on the online line, but he will give me discount that will bring my payment to R900 something instead of the R705 that I have already paid when placing my order. I told him that it is not going to work, so please just do a refund with IMMEDIATE payment. Then I received a sms of the payment on what I again ask Yunis if it was an immediate payment, on what he rep**** that he forgot to tell the people to do an immediate payment. My husband tried to talk to the owner on what he started to get rude, so there is no way to have a proper conversation with Yunis. I feel that if you have made a mistake, take ownership and responsibility and honor it and then correct the mistake afterwards, but you cannot ask the client to pay up because of a mistake made on your side.