10Mbps only getting 4.29Mbps

For the past 6 months i have only been getting just above 4mbps on my internet speed. I am on telkoms 10mbps uncapped package and I only want what I am paying for.Is that too much to ask. When I phoned Telkom this morning regarding my problem they wanted to know if I would be willing to downgrade to 4mbps. NO No No I just want what I have been paying for the last 6 months.Telkom is useless!! I have been with them for almost 22 months and pay almost a R1000pm so now im tired of this and think I need to take my business elsewhere.