Refused contract cancellation

Wanted to give the required 30 day notice for contract cancellation with CellC today ( I'm not sure why this is a requirement anyway, we have a 24 month contract , and 24 months has lapsed, so that should automatically be end of contract). I was informed I could not hand get the notice effective today since there is currently lockdown. I spoke to someone from the call center who informed me all of this. Why could they just not log the notification? I find this quite convenient for Cell C. I now have to wait at the earliest 17 April to start my 30 days, despite Cell C clearly receiving my communication and intent to cancel.