This may sound silly but have you plugged the speed controller fittings into the reciever the right way round? if they are reversed then there will be no power to the reciever.
Brown - earth
red - live
orange - signal

Have you got a meter so you can check that there is a voltage across the red/brown wires when power from the battery is applied to the speed controller? If there is no current then the sabretooth is faulty and should be returned, if there is current it may be the reciever.

Can you get to Guildford on Sunday?