Disappointed client

I called MTN and I spoke to Minenhle and he couldn't resolve my query and I asked him to get the team leader and he said team leader is off asked for the manager he said the very team leader was the manager I don't understand why we're not allowed to speak to me the superiors when agents fail to resolve matters I have been calling MTN since January to date no resolution I am supposed to be reimbursed for the money they're billing me despite that the router is cancelled and has been returned to them I'm very disappointed and angry 😡