www.jec.org.uk

Having owned my Celebration convertible for 3 weeks the speedo and cruise control stopped working, I used a garage that was recommended to me and talking on the phone they seemed to know what the problem was.
They plugged it into their Jaguar dedicated diagnostic equipment and the fault was the speedo sensor, which they ordered from SNG Barretts @ £69, only to find when the new part was was fitted it did not solve the problem. After further investigation they found a broken wire from the sensor to the interface unit broken.
When I picked the car up I was given an invoice for £256, the old sensor was not in the boot and they said they could not send the new one back. I feel they should have done the investigative work for broken wires before ordering new parts.
I feel like I have been mugged.

I am not a lawyer, so take the following with a pinch of salt:

It's reasonable to check out electronic parts by substituting a known good one to see if that cures the problem. But if it doesn't, it's not reasonable to still take the money. My guess is that whether you can get your money back depends on how the replacement part was "sold" to you - i.e. if they can show you asked them to replace it, then if it doesn't work that's your problem. If they said they were replacing it to cure the fault, it's their problem, as it didn't. A chat to your local trading standards officer might be in order...

Thanks Paul, good advice as I did not ask them to replace the sensor.

The garage has refunded £156 to me, thanks again Paul for your advice.