Bad service from Cellc

I cancelled a 240 add on voice minute bundle on 28 February 2023. I was told that it has been cancelled, but on 1 March the bundle was back on my account and I was charged for it. I called them on 1 March to enquire about this and was informed that they will investigate and will get feedback within 48 hours, but it is now 5 days later and I did not hear from them. I cannot even use my phone for fear that calls made will come from the 240 minutes then they will say, “but you used the minutes”. I’m so angry with them because I’m losing business.