A truly horrible experience

We had booked on Lufthansa but were moved to SAA when they cancelled overnight flight. We made very sure to specify dietary allergies to SAA. We took time to select seats as my brother has a knee injury. Our flight was CPT to JHB to London. I noted that I was given a Halaal meal which I was told was Gluten free. I had all the symptoms of ingestion and spent the layover in JHB throwing up- a side effect of gluten. My sister was also give the same halaal fish meal even though she asked for diabetic. SAA then changed planes so the seats that we had chosen were now forward. My brother had no leg room. My brother had a singularly unpleasant flight due to his injured knee. The staff were unhelpful. In addition, before they sprayed the cabinet, he was bitten on the back. We tried to tell the air hostess that we had dietary concerns. We were rudely informed that we should have made that clear when we booked! Being snapped at by cabin staff is not on. If dinner was bad then breakfast was worse. I essentially had 4 rice cakes. <br> Also the seats were the most narrow and uncomfortable we have ever experienced- space being taken up by the media armrests. This was the first and last time on SAA.