Opel Astra diesel not revving

I brought an 08 opel Astra diesel to Nct for a friend.On the way it was driving ok for part of the journey but then I could not get it past about 60km per hour.The hand brake light was coming on intermittingly and I noticed that the spanner light was on dash when I pulled in to Nct centre.I dont know if is was on all the time or not.Anyways the car could not be tested because it would not rev up and the test fee was refunded.On the way home the car drove pefectly and there was no spanner light on dash.The hand brake light is still flashing though.The reason I am mentioning the hand brake light is that while searching the internet someone had a similar problem on a Zafira and he was advised th change brake light switch??? Would anyone have any idea what the problem might be.