False premium given - Discovery insure

Took out a policy through "Discovery agents" - who it turns out are actually DGC - BLUE MERCURY. The advisor Sebastian, gave a premium of R3800 - when I went onto the policy documents the premium shows R4300. I phoned DGC - BLUE MERCURY and spoke to Sebastian and told him if he cannot give the premium he promised on the phone then he must cancel the policy. I went onto my discovery now, and see that the policy is still showing active to commence on 01/12/2021. This is absolutely ************ behaviour by someone representing Discovery and to LIE to a client on the phone is totally unacceptable. I want this policy cancelled immediately and to understand why this agent has been allowed to operate and if this company DGC - BLUE MERCURY is actually a representative of Discovery.