Supersonic riding the MTN brand but failing to deliver

I have been trying to liaise with Supersonic for ages now to do a basic upgrade on my fibre line. I have been forced to use their whatsapp service which is awful to say the least. Their call centre individuals send messages shortly before 10pm (thats when they close) keep promissing to contact me but never do, i have had failed attempts on several occasions, not to mention my previous 100meg fibre upgrade runs very slowly (did speedtest turned off everything and spoke with an agent).