Amazon are *****. They dont honour their word

I bought 4 kindles on a promotion on prime day. I live in south Africa but my best friend lives in USA. She was flying down to south Africa on the 24 July 2019. So on the 15 July 2019 I asked her if I could buy these four kindles for my kids, one who's birthday was 5 August and the other 3 birthdays are all in November and she agreed and said she would bring them to me. I then in good faith ordered them and as a prime member was promised the date of 17 July 2019 for delivery. The date came and went but no sign of the kindles. So I call internationally which cost alot and explained my situation. I said urgently I need these kindles before the 24 July. After some time of arguing about this, the support guy spoke to his manager who agreed Amazon was at fault and promised me that if the kindles did not arrive by the 24th August they would post them to south Africa, with no shipping or customs cost to me. On this basis I did not worry. I asked them to email what they said to me so I could have it in black and white and they did. Also they had taken the money from my credit card. So today I called them to tell them its 24 July, my friend has left for south Africa so please to send me kindles to my south African address. They refused to do so. Saying if I cancelled I'd have to pay the normal price and shipping and customs also at my cost regardless that I have an email from them in black and white. I wasted alot of money on these international calls and am highly upset as now my sons birthday gift which I showed him he will not get as well as my other kids. I was promised that due to their mistake of not giving my kindles in time that I would be posted them and they are not doing that. I wish to post on here their emails so that others can see and not buy from Amazon who does not honour their word at all.