Cellc failed me.

I settled my cellc account in 2024 around June, n yet dey handed me over to nu debt, these people keep on debiting 160 in my account any time they want with a fail as there's no money n leaves me in a minus...i spoke to Some1 on the phone from nu debt that I settled my cellc account n they sended a paid up sms...my question is why did cellc hand me over meanwhile I settled their account before the contract expires? And why is nu debt debiting my account without my concent?? Isn't that *****?