My mother is a pensioner and I am looking after her

My mother is a pensioner and I am looking after her. She is on Keycare Plus and we have been paying R1825 per month for her basic cover. Suddenly we get notification on 28 Dec, right after Christmas and just before the new year that her premium will be going up to R4200 per month and will be deducted on 02 Jan. This is ridiculous! We have not been able to get in touch at all with Discovery telephonically, they are simply unreachable and we have sent several emails with bank statements etc to prove that my mother is in fact a pensioner and we can't afford this exorbitant amount suddenly. This is blatant *******! They went ahead and debited my account anyway and after an hour of wasting all my airtime to add insult to injury still no answer on their phone lines. I can't believe how they can just decide a few days before the New Year without any sufficient notice to just more than double the premium??? Absolutely disgusting and no service at all from their side to try and rectify it.