Intentional over charging, customers must check adverised prices against till slips

I've emailed orders, contact and CEO at Leroy regarding the false and devious manner of charging from online advertising to final stores purchase at the store cashier, no one has responded. The online price was advertised as a promotion at R799.00, at the store the shelf price and attendant confirmation was R899.00, the cashier charged R999.00. I returned to Leroy Greenstone, spoke to Dudu, the store manageress, she advised it was only available to card holders, at the online price, but could not explain the additional charge of R100.00 at the cashier. I said I was never given a card, but have done on-line purchases, she took me to the cashier, entered my cell number, and discovered i am a 'rewards' customer to which I received a refund of R200.00. The promotional price does not reflect the requirement for a rewards card or only online purchases, the shelf price shows a reduction of R100.00 and the till price is the shelf price plus an additional R100.00, why ??? At my inconvenience, requiring another trip to the store, I am immediately attended to by the manageress, given a refund and an apology, but no explanation or compensation for my efforts, how many more customers are being taken in this manner??