Black Friday Nightmare from The Proshop

I bought some merchandise online on the 23 November 2018 as part of Black Friday specials. I bought 3 golf shirts and a short. I waited for the whole week without any feedback. From nowhere yesterday I get this email from The Proshop indicating that they had a technical glitch that made them to sell more goods than they could source and now they are cancelling my order and refund my money.

To add the salt to the wound, they are offering me R100 to use towards any future purchase at The Proshop. My questions are: - Why did it take them more than a week to realise that there was a technical glitch? - They accepted my money (over R800) and now they think that they can dishonour the purchase agreement we have, how does that work?

You can't even get a telephone number on their website so that you can talk to them in person. I am very disappointed at their service. I have purchase golf merchandise from them before and I had no problems, I am surprised what has changed now.

I am not going to accept their R100 offer, all I want are the merchandise I ordered and paid for.