Double monthly billing bad faith

I have realised that FNB does not respond to you when you try to resolve issues with them internally, only when you log a complaint on a media platform that is when FNB attends to your query. I requested to downgrade my account to their savings plan beginning of October which they failed to do, I went into the branch earlier this month in Johannesburg, They downgraded my account but billed me double, billed me for a gold cheque and also a savings account, I laid a complaint and till this day they have not responded to me, but they keep charging my account extra. ridiculous I am lost for word, FNB keeps on disappointing me on every turn.