Vumatel and Cell C - lying to customers on top of bad service

Paying for a 1gig line, suffering service degradation on speed and intermittent dropping. Logged calls, phones several times, emailed several times, but they are not resolving! I have been assured by more than one person, including a manager that my call has been escalated, yet the last call i made the agent said my call was NOT escalated due to it being within the SLA????? So, who is telling the truth?