my astra 53 plate keeps reving high then low between 800 rpm and 1200 rpm and the speedo goes to 10 mph then 0 when its not moving

what can i buy as a tool to reset airbag etc and find faults like this i have come accross some on ebay that do loads, yes wait for it any garage dealer or mechanic will tel you there shit so you dont do it yourself and take it to them..

well the one's on ebay that sell disc's etc have got 100 per cent feedback so thay must do some good

dont want to spend silly money only around £150