Wrong order caused allergic reaction on a pensioner 😠😡

We ordered sit in on saturday 04June @mall of africa nandos. I specifically asked for no flavour tea for my mom. We waited over 30 minutes for our order was told that they thought it was for take away. Than my mom's tea was accompanied by a small box masala chai. We continued with our meal and she had the tea after few sips she complained that it tastes diffrent i cheecked the box it was empty so my mom was served masala chai that we didnt ask for. Next morning my 79year old mother woke up with allergy her whole left side is swollen. She didnt eat or drink anything diffrent from what she normally eats/ drink accept for the that flavoured tea. I specifically asked for no flavour tea as i know my mom. We had to get medical help for her allergy she is still swollen. This is really really unacceptable.😠😠😠😠😠😠.