Vodacom Fibre **** Speed

I migrated my home fibre from 10/10 to 20/2 to 50/5 , the 10/10 was stable and never had an issue with the Data transfer Speeds and stayed at required speed .The 20/2 migration was also a good transition with 20/2 being stable at required speed. I then stepped the line up to 50/5 migration , this was the problem , ever since the migration the line is unstable with as little as 10mbs to 38mbs on download with the upload stable at 5mbs. I was contacted by Vodacom to connect my PC directly into the LAN cable to "get the correct Speed " using a link provided, this was done and best result achieved was 38mbs .This was sent to them and they received this. When checking later the line was unstable with results of 10-15 and 20mbs download speed. I have numerously contacted the 082_190_4 line with no success , I have Spoken to Luthando the Fibre team leader, and many others .I have been numerously disconnected whilst on the line as well .It is frustrating to get a simple thing like this sorted , I wonder if a person could get what is requested ,and what one pays for .This is the second Review , as the first was ignored without anyone getting hold of me .At this point any feedback would be appreciated. The Fibre centre is inadequate to say the least . Does Vodacom expect payment ,is my next question for something as I don't get what I am supposed to pay for ,I am at point where if not sorted I will reverse upcoming payment