1 cent payment

I booked and paid for a Mango flight from Jhb to PE last week. After booking online I paid using my voyager miles for which I had sufficient miles to cover the flight. The booking showed up no problem. 24 hours before my flight I went online to check in - it showed I had an amount outstanding of 1 cent. It would not let me do an online checkin until I paid the 1 cent. I called into the Mango call centre and after holding for about 15 min my call was answered but they had no idea what to do with my problem. Eventually they told me I had to pay the 1 cent. I felt this was completely ridiculous as the bank charges on the transaction would far exceed the 1 cent but I was travelling with my toddler and I wanted to save time. So I put in my credit card details and attempted to pay. Behold - it would not let me. Another 20 min on hold to the call centre and then being placed on hold a few more times I was eventually told there was nothing they could do and I should contact customer care????? For what????? I went to checkin at the airport on the day and believe it or not they asked me for my credit card and I see on my account now they put a transaction through for that 1 cent!