Go Bike Forte Trike Controller problem

[Puddy]

I have a new Forte trike that doesn't work. The distributor gave up, refunded my money and left me the trike due to shipping costs to return it. It's a beautiful heavy-duty trike, but it's brain dead! When the throttle is pressed or pedals activated, it wants to reach its max speed no matter where PAS is set. Walking the trike it shows 10kph on the speedo which is impossible. I'm thinking that I need to replace the controller but am having a problem finding one that fits. The controller is DC48V, and the motor is 750W. Measurements are Length 4 1/2",Width 2.0" Thickness 1 1/4". The display is SW900. I'd appreciate if anyone could give me a lead on where to find a new controller that might fit. Maybe the controller isn't dead? Anyone with any ideas on what just may be a problem if it's not a dead controller? Thanks.