My friend visited Vodafone yesterday and had her phone check out... all working.

A bit difficult to ascertain exactly what had happened.

The $0 probably means that the $20 topup refreshed the $20 Myflex plan with $0 balance.

I think yitz may be correct in that the 17 March shown on the phone after topup means the Myflex plan is active through to 17 March 2022.