poor service

I have a 10mb line with afrihost and when I try to stream Netflix it's not working YouTube streams and stop. logged a call with Netflix first which we did some test on the same device when connect to cell c and vodacom network it streams fine. Then logged the call with afrihost sent in all speed test and all required but a lady by the name of Lerato mabena come back to me and say it is a Netflix issue. why is my YouTube doing that if it was netflix and why is it working on other ISP.