Mango Airline, will never use them again!

I paid for 2 Tickets from Johannesburg to Zanzibar, i booked and paid for the tickets online, payment was done the same day as the booking. I received a confirmation letter from Mango with our seat numbers which i had to pay extra for, i also paid extra for over weight baggage which all came up to R16097.36. Payment was done money went off my account. We arrive early Saturday morning at 5:30 at OR Tambo to check in, the lady tells me she cannot find my flight booking and looks like they cancelled it that morning and that i had to go to Mango desk to find out why. The lady behind the counter said to me that payment was not done and was cancelled the day after i had made the booking, and that i would have to pay another R16097.36 to be able to go onto the flight to Zanzibar!! I then showed her proof of payment on my phone that this was paid for and asked her why her story was different to the lady at the check in, NO REPLY, got up and went to the manager at the back, 5 minutes later she comes back and informs me i have to please send the proof of payment to her Manager. Finally after much effort and problems we were able to send it through to her, but it doesn't stop there! She informs me that she thinks it was a Technical Error and will have to find out by the IT guys on Monday what happened and if my payment reflects, my flight coming back was also cancelled and until then she cannot reinstate my ticket back. I booked and paid for seats, was given other seats, the seat my husband sat on was broken!! The seats i booked and paid for was empty.... i was told i cannot get my same seats as they were already booked after they cancelled my bookings. I had to leave South Africa not knowing if I was going to come back on my day booked. Monday afternoon after emailing Mango again regards to my flight coming back, do i get a letter saying sorry & yes we found your payment and was an IT problem, my flights coming back would be reinstated and if i had a complaint to contact their offices. After 2 weeks arriving at the Zanzibar airport to check in, was I told that i did not pay for Extra Baggage!!!!! Finally after a few minutes and getting upset with the poor guy who was sitting behind the desk he just let us through. Once again paid for seats and got onto the plane and was not allocated our paid seats, they hardly had any food which was advertised on the menu in the book, and ran out of ice before they got half way to serve everyone. I had no contact from anyone from Mango airline after that, no one referring to seats which i paid for and never received or to offer a refund or any Managerial Person contact to apologize for any inconvenience caused. We had to rush through our breakfast that morning because we were held up for almost an hour at the desk trying to get on a plane with our friends who was traveling with us. Cannot believe this airline company! Will never use them again,