Incorrect item delivered

I bought canola oil which was in special buy 2 for R100.00 and i bought 4 I didn't choose the alternative because I did want to replace it. The price for the alternative is expensive. I ended paying R300.00 for the oil instead of R200.00 . I am not happy about the alternative the canola oil I use it for specific thing. I need a refund on these. I called them n they said they don't offer refund over the phone I need to go to the shop. I bought my grocery online because I don't have transport now I have to use R100.00 to go get a refund of R200.00 for me it doesn't make financial sense. My order number is ***