Cancelation not processed

Phoned to request immediate cancelation of a 5G sim, they assured me this would be done. The next day the app indicates cancelation scheduled for the end of the month. Phone them once again and told the same thing, they will escalate for immediate cancelation which has still not been done. Please confirm the cancelation will be done immediately and I will not be billed beyond the 3 May (initial cancelation request submitted)