ticket error and assistant insisting i did not pay

Yesterday around 17:00 i paid for my parking ticket. i always Park at the R15 parking opposite Table Bay Hotel. as i was driving out i inserted my ticket and it said return to teminal. i buzzed for help and the assistant was very rude. i explained that i paid and the ticket is actually written paid and she said go pay. she asked me to insert my ticket on the camera according to her and she said its not paid. i looked for waterfront security who checked and said you have paid. he buzzed her and she insisted i did not pay despite him explaining that its paid and that i park there everyday. she then said a lady will come there, i waited and the two ladies looked at the ticket and said you have paid. opened the boom and i left. i spend close to 30 minutes there. i was late to pick up my kids and had to pay extra for extra time. what hurt me is the customer care i got. despite the fact that security was there explaining the fact. she is sooo unprofessional. as i speak the money went off my account