Premium paid from my account which is not suppose to be

My sister and I have taken a policy for my dad Mr TP Makongoza. The policy is mine and my sister has her own. We were both paying the account seperately. The problem started Decemebr when my sister missed her payment and they sent me an email that i missed a premium. I sent so many emails explaining who i am and who my sister is andthat the accounts are 2 different accounts. My sister then paid her account for december on the 21 January 2021. On the 26th January thuy diducted double the premium from my bank account. Then still I communicated with them that they deducted double from my account for what. And still my sister missed her January premium and now i have received an email that they will take money from my account. I am so angry right now because they are messing with my account. My name is Ndangano Mashashane and my sister is Matamela FB Makongoza.