Travelstart inconvenience

I’ve been trying to change my flights for a trip since the beginning of this week. The flight leaves today at 14:00 and my return is for Monday. Travelstart only responded yesterday and gave me the wrong date change, so I couldn’t even pay the difference so that my flights for April are sorted. Their WhatsApp system is appalling to say the least. There is no urgency whatsoever on their end. Someone tried to assist me on WhatsApp this morning, but I wasn’t even sure how long that would take. I missed their calls and tried to call them back. I waited to speak to an agent for 30 minutes and after that l, the line just went quiet. I tried calling again and my calls didn’t even go through.