Account Not Debited

I am soooo angry with Cell C contract department, I have a phone contract with them that was debiting on my Tyme bank account. I changed to Capitec account on the end of October 2023, and it has been debiting since then until end of March. I phoned them to enquire why no debit went through. I was told of a debit mandate that was supposed to be done by them for the March payment. I have been transferred to all departments spent over 2hrs in calls to find no help. I have all that I could to sort this mess out to finding no assistance or joy with Cell C. I AM NOT PAYING ANY PENALTIES FOR THIS...