Dash message says hood is open when it is closed

Sorry for a stupid question. So for the last 3 weeks it is coming up on my car that my bonnet is open when it is closed my window wipers don’t work until I drive and only come on at 6 MPH and stop working as soon as I slow down, my windscreen wash does not work either and my auto start as well has stopped working, I’m nearly sure due to the bonnet saying it is open. I have taken it to 3 different garages and 1 garage has said get a diagnostic check and I got AA to do it and they couldn’t find the problem, another garage had told my that my bonnet latch with the sensor cable is perfect and it could just be a loose wire, but it gets better I have looked for the part online and it come second hand with a year warranty for £65 but this garage is charging me £250 to remove my old one and fit a new one when the mechanic has said he is 88% sure that is is the bonnet catch and sensor but I’m unsure. Has anyone else had this problem?