Auto Electrician Job - Meyerton, GP, 1961

We have a problem. The car cuts out when driving and then it is as if the battery is dead. We do not belive that it is the alternator because while driving, if you put the indicators on, the rev counter drops, so it is possibly a short somewhere. What would the estimated cost be of repairing something like that +/- and can we possibly bring the car in today? Where exactly are you based? Thank you.