Not great, early cancellation notice given on data sim only contract - notice period as required by CPA 20 working days

Not great, early cancellation notice given on data sim only contract - notice period as required by CPA 20 working days . Notice given 2nd May to be effective 30 May . Early cancellation quote received and paid , all bills up to date . Vodacom went ahead and processed cancellation , terminated service and data allocation lost - effective 6th May (over 3 weeks early) Then issued additional invoice for airtime on that line that no one can explain - no billing or cancellations and the invoice contravenes Vodacom contract terms and the CPA Unless someone can explain the invoice I guess we will be seeing the ombudsman or small claims court!