Scammers - Poorly Manufactured Blocks

On the 14th October 2021, I bought 1000 blocks from Cemex blocks and paid the money upfront(they usually do COD). After weeks of requesting for delivery, they finally delivery 400 out of 1000, then 400 a month later. I had to fly back home from JHB when the builders told me that they will not be able to build with the blocks as they are breaking into crumbs. I then took a video of me squashing the blocks with my left hand and sent to Cemex blocks to see how the blocks breaks into crumbs. They requested to pick up the block and replace tgem with others. I thrn asked to come and see the blocks before they deliver, only to find out it is the same poorly manufactured blocks. I then requested for my money back. The owners boyfriend was very rude, insulting me and kicking me out of his yard. The owner then came out of the office and told me that they will give my money back after 14 working days wich was the 14 Dec. I then asjed them to put everything they are saying in writing. To this date, I have not received my money and they no longer pick up my call. They are no longer onsite only the workers are there. These people has scammed a lot of my village grannies. Please help me expose them and get my money back.