Advice on faulty speed sensor

Hi there,

I was wondering whether you can help me, I have a faulty speed sensor on my Vauxhall Tigra, 1997, Auto, 2 door, I know its the spees sensor as it also contols the speedometer and thats not working I hardly get any movement from the car, can you help?

How much would it cost to fix?

Regards,

James00