Based on that it sounds very much like the speedy is not setup properly.
Have you gone through the speedy setup sequence? You need to set it up so that your radio and speedy think they have the same maximum speed and brake.
That is: When the throttle is on full the speedy knows it's full throttle and when the brak is fully on the speedy also knows that it's fully on.
Most speedie's have a one touch setup which lets you do that.
Anything like that in the manual?
Tony