Telkom nightmare

I`m battling with Telkom since July 2017 , my internet speed is way below average , so I decided to get a 4mg line and later a 10 mg line . Since I have the 10mg line my speed was not once above 6 mg and it is very intermittent. On a good day it average 6 mg but most of the time its just below 2mg. From the 15 th February my line is completely dead, I cant get any incoming calls , no outgoing calls , nothing ! I complaint numerous times , 2 January Ref ********** 5 , 11 January Ref ********** 8 , 12 January Ref ********** 8, 15 February Ref ********** 2 and today again on 5 March 2018. What must I do to get a decent speed and a service form Telkom that I`m paying for ?