SAA SUCKS BIG TIME

My son originally booked a flight to Heathrow on 5 October 2016 to fly on 15 December 2016 and return on 10 January 2017. Unfortunately my knees started to trouble me and I had to have an emergency knee replacement operation on 21 November 2016. When I contacted SAA Customer Service they told me that I was unable to cancel my ticket and receive a refund but could extend the ticket. My son extended the ticket on 13 December 2016 so that I could still use it. The date that I would fly to Heathrow was 10 September 2017 and return on 1 October 2017. He paid R1721.00 surcharge. I had my second knee replacement on 15 May 2017. On 20 June 2017 we again changed the dates as my UK family could not accommodate me in September. The dates to fly were 9 December 2017 and return on 30 December 2017. A surcharge of R2950.00 was paid. When I arrived to check in I was informed that there was no ticket issued for me and was told to go to the SAA ticket sales counter to enquire further. My son was initially helped by an obstinate sales person who simply said pay R14000 for a new ticket as they can't help with SAA online centre bookings. He came back to us with this answer but we weren't satisfied. Gratefully when returning to the sales counter the unhelpful sales person had left to attend to something else and the team manager was on duty - Mpho. She said that she is unable to investigate but would contact online call centre for us. For two hours the call centre just said no sorry this ticket had expired 30 Oct 2017. When asked how is it possible after having paid for a change to the ticket and receiving confirmation with an itinerary and flight reference for 9 Dec. No then we must have done the extension after the ticket expired - no we didn't we did it 20 June 2017 and if that was the case why would we be able to extend it after expiry? Eventually the call centre spoke with Mpho and asked them to give us a quote on price difference between the original ticket and the new quoted price and their cost centre would then pay the balance of the new ticket R9000. The only way I was flying that evening and now on a later flight was to pay up. On arrival at OR Tambo on 9 December 2017 we were informed that I was not booked to fly. After much wrangling and discussion my children had to pay a further R5 374.00 to enable me to visit my UK family. How many times must we pay for a ticket? In total this journey cost my children a cool R22 769.23. I find it quite unacceptable and a refund is necessary. Somewhere along the line ***** was committed as my flight for 9 December was confirmed by email under BOOKING *** DATE: 20 JUNE 2017 I was told that if I had died before flying my sons would have been refunded. So what is the difference if one has a legal medical reason for being unable to fly?