I contacted the manufacturer and they say this : Becuse of the CPU of the router and the quality of the network adapter in your PC, it is normal that there is a 50-60KB/S losing.. So I will ask him if that means if I bought a router with a better CPU I would get a faster speed. I'm using a wired gigabit connection that has no problem maxing out around 100MB/s so it shouldn't be that which is losing the 50KB/S.
I found a way to soft reset the QoS, there's an option for type of line, ADSL or other, when I choose other it downloads at 580KB/s like when QoS is off, yet its still turned on (just not functioning, when using another PC it would only push my downloads down to 400KB/s - the same as when QoS is off, not 100KB/s like if it was working properly). To fully turn off QoS needs a router reboot and its annoying and can connect at a slower speed especially if at night.