Very bad Service

I called MTN to black list my child's phone as it was ****** from him and the call agent I spoke to on Monday 2022-06- 27 said he will assist me took all my details and said I will receive the ITC number via SMS I did not then today on 2022-07-01 at about 12:30 I called them again and now they telling me they can't black list the phone I was not using it....they need to talk to the child first would I waste my time to call them and report a false case this is just being unprofessional