SB Stationers terribly poor experience

Highly disturbed by the service I’ve received from SB Stationers in East London. On Monday I contacted their WhatsApp number requesting the price for oximeters, I was told R299. On Friday I went out of my way to their store to find suddenly they are R399?? Firstly the manager tried to say it was a price increase then came a story of it being new stock?? I left them a review on Facebook for the poor service and conflict in pricing. I was then contacted directly by Belinda threatening me to take action against me if I did not remove my Facebook review!!! What type of business threatens customers over a negative review? Normally a good business owner will apologize for the inconvenience and try to rectify the situation but instead I got an inbox message as well as a comment on my post telling me that they are “no longer standing for this nonsense” and that they intended to take things further should I not remove my review. Subsequently I will now post a review on every possible forum as is my legal right to do so. Shame on you SB Stationers.