Supersonic Fibber

We have a 10/10 or 20/10 fibre line backed by Vumatel. Speed tests give us around 4 down and up with a Mtn connection. What happened to Vumatel. Complaints to Supersonic are a waste of time. One 'escalated ' phone call, and two emails with speed tests and case number Cas-750960. Nothing. Nada. Niks. Just the sound of silence. How can we be receiving MTN business through our fibre line. Sometimes nothing and sometimes well below 1 mg. We could have been better of on Rain. Very poor service from Supersonic when they dont even respond. Plenty complaints here on Hello Peter