Promise in writing overturned verbally

FDX-***1 Hello Peter, We have some great news!

The monthly price of your Octotel Fibre package will decrease on 01 December 2020! Our mission is to make sure that your data delivers what you need and that every byte counts. You'll still get the same uncapped experience you've come accustomed to, but for less. And best of all - this is not a promotion. This will be your new monthly package price going forward. It’s just our way of giving you even more Pure Internet Joy! 100Mbps+ Octotel Pure Fibre 867.00 PM What you used to pay 767 PM What you'll pay from 01 Dec 100 PM What you save They have now verbally told me that they are NOT going to honour this agreement as it was sent in error. 1 st December I paid R767 and the 1 st of January I paid R767 Now they have made it R967 without even letting me know. By the way this WAS NOT PART OF THE PROMOTION.