Thank you Bob for your response but you really haven't given me a reason for the problem with my fuel gauge.
I am fully aware that if the new sender unit is faulty or becomes faulty within twelve months it will be replaced under guarantee. This written on the receipt from the garage.
The rest of your reply indicates that I need to go back to the garage and have them test the electronics to ascertain what the problem is. Naturally, I was going to do this anyway as it is the only course open to me.
What I had hoped you would be able to tell me is that this was a known fault and that by replacing/adjusting a certain componant would rectify the problem. Armed with this information I could then return to the garage and suggest that they inspect that part and justify to me why the replacement sender unit had not recified the problem and should not have been replaced in the first place.
The garage state on their invoice that they carried out a computer check on the gauge and found that it was functioning correctly and they charged me £45 + VAT for doing just this. The total Invoice was £365 and I have reason to believe that the sender unit was not the problem in the first place.
So once again, thanks Bob but you have not given me a difinitive answer to my problem.
I shall be very glad to provide more information if it will help. Due to family circumstances I am not able to take the car back to the garage for around three weeks so this may give you time to research and give me a more definite response.