Online check-in & bad service

This is the first time I have used FlySafair, I am very disappointed with the level of service experienced. I bought a ticket more than a month ago from my departure date and I struggled to get payment processed using my credit card. But eventually was successful. <br> <br> I check-in online exactly 24 hours before flight departure. The online check-in was successful and I was emailed my boarding pass. Upon arrival at the airport security (ACSA) they scanned my home printed boarding pass and said there was an error but just override it with no explanation to me. <br> <br> When I was attempting to board the flight I was told my flight ticket was invalid and the supervisor had to be contacted to get me on the flight. I had booked seat 3D and was allocated seat 16C, a middle seat at the back of the plane. I was travelling with a colleague and we had booked seats next to each other in order to continue with work. I took the new seat, as I was promised the flight attendant would relocate me once we had taken off. The flight attendant was not helpful in this regard and never came to check up on me or move me to an aisle seat as I was lead to believe would happen. She basically ignored me.