I would have to say that 1.33 mbps is not too bad when you're supposed to be getting 2 mbps. However, you're right, you should get what you're paying for. Thing is that's how the Internet works sometimes. There might be times when the speed gets slightly slower due to a variety of reasons. I found this on Afrihost's FAQ page, but this one's for DSL - I believe you have Fibre?
"The up to 4Mbps and 10Mbps DSL services have sub-profiles, which are used to stabilise a client's service that experience re-syncs (service interruptions) on their DSL lines due to a variety of factors, such as last mile distance, noise and attenuation. "
Anyway, I would suggest restarting your router. Check if anyone else is using the Wi-Fi connection. Wait just for a little bit. If this is what you're usually getting, like 90 or 100% of the time, best to call Technical Support for assistance.
Best of luck! :)