MTN Debits Account Without Prior Notification & Ignore All Comms

MTN took it upon themselves to not debit my account as per the norm only to ‘realise’ 6 months later that they’ve made a mistake (which they don’t acknowledge). The ‘realisation’ came after I contacted MTN to query my account! Instead an email with a threat to blacklist/assign the account to a collection agency is sent. In response a follow up email is sent to state that the error is not mine; instead MTN without prior notification or approval debits 6 months worth of debit orders to ‘bring the account up to date’. With whose permission? Whose fault? I’ve made several calls & sent emails I’ve been blatantly ignored. Your service is appalling- be accountable for your mistake first of all & communicate with your clients before making erratic decisions that affect a customer financially. I’ve said I want to cancel - again I’ve been ignored. One thing is certain, I’m not done with MTN until I get to the bottom of this.