"Check Engine" Light Stays on - LandRover Discover

Dear friends and webmaster,

We have a 1998 Landrover discovery. Our car was sent for maintainance early November and was told that the computer code showed that the charcoal canister needed replacing. The second day after the part was replaced and the car was tested all right, the "check engine" light went on. We called the dealer and was told that it would be free to get a new part if the warning code showed the replaced canister had defects.

We went the 2nd Landrover dealer (coz we moved after the 1st repair). The dealer simply contacted the first one and checked the replaced part. As it was defective, we received a free labor work and a new replacement. However, the 2nd day after we got our car, the "check engine" went on again. This time, the service person at the 2nd dealer sweared that they'd given the car a good road test. We asked whether there could be a wire disconnection somewhere which had triggered the light. We drove there and asked them to find out what had happened.

Two days later, the service person called and said that it was the computer board (forge), which would cost $2,500 simply for the part. We wanted our back for a 2nd opinion. And the service guy mentioned that there would a diagnosis fee. He didn't say how much.

When we went there on Saturday, we found that they charged us 3.5 hours labor work for diagnosis and the cost is about $400! We wanted to talk to the service first before we pay. So they kept our car.

I went online today and found that the dealer needs to ask our permission if any labor time or cost exceeds that of an ordinary check. And the three reasons AAA lists for "check engine" light on has nothing to do with computer board error.

I would like to ask whether we have a point to challenge why they did not ask for our permission first when the work would take 3.5 hours, whether this is unusual that a diagnosis costs $400 and 3.5 hours, and whether they had responsibilities for not finding out the problem at the first and second check? Thank you very much!