Who do i call - Car not starting

[centurian51]

today is another day and another problem, jumps in my Connie today puts in key ..nothing car does not crank cant work out whats wrong however when i turn the key there is a humming noise which appears to start somewhere above the pedals and on opening the bonnet can be heard quite clearly. I decided to call out breakdown Green Flag they to could not identify the problem but he suggested there was a problem with the immobilizer in his report he wrote
"No voltage at signal wire direct 12v applied to starter which cranked but would not fire/could not identify component." He suggested i call out a tec guy who can do a fault code reading however when i tried to find one they said they do not deal with immobilizer problems so who do i call cant take it anywhere cos it wont start any advice id be great full for is is also possible the codes lost, it unlocks and locks but wont allow the car to start