Paid my account in full and still being debited

I equestrian a settlement figure in november 2017 and I paid the amount in a vodacom store I sent an email to ********** no response was given i phoned in december 2017 the gentlemen assured me the account is closed and put to prepaid...I received a invoice for vodacom in January 2018 I was told the account is still not closed and they will sort it out and behold I have been debited for R133.49 ...I have proof I settled this account was told twice it will be closed ...what service is this????? I'm disgusted from this and going to the NCR.