Black Friday deal not met - will not accept

I ordered a Black Friday deal in 24 November 2018 at 06:00 am. It was for the Samsung Galaxy A8. Telkom has debited me with R249.99 and now claim they do not have stock and that I have no choice by to take the A6 Plus. There are significant differences between these 2 models and I refuse to accept something other than for that which was contracted for. Telkom cannot lure customers in with a deal only to tell them they are out of stock. I cannot accept this and want delivery of the Samsung A8.