Waiting period for non-chronic illness

I just added a dependant on my medical aid. On the form where they asked about the health of the dependant, they asked if the child had seen a Dr recently, I mentioned that she had swollen salivary glands, something that was only caused by a weak immune system after she had been sick a while. A bacteria she picked up at day care. When I added her, they approved the addition on condition that she be put on 12 months waiting period for the \salivary gland condition". I protested this because it is not a condition but an illness that she had at that time (more like the flu). They asked me to get an underwriting from my Dr to confirm that it was not a chronic condition"