Poor service from Vamatel

We got a 1000mbps line but for the last couple of days our line speed has barely reached 400mbps. I have logged two calls with Afrihost as they need to escalate to Vumatel. After 2 calls logged, no success. What is more frustrating is that there is no way in contacting Vumatel directly. POOR POOR SERVICE AND NO CUSTOMER RELATIONS AT ALL! I am cancelling my service with immediate affect.