To find out which one's failed, start up engine, get somebody to sit in car with foot on brake (firmly!) and test front ones in D and rear ones in R. Put your ear over each sensor. You should hear a faint clicking on each if it's working. One that's not is the culprit. If you get a long beep for a few seconds when putting in reverse the it'll be a rear one that gone.
Hi Richard,
You could try the site below they clam
All of our glass comes from the same manufacturers who supply glass to the car factories. Therefore, our glass replacements meet all the original equipment (OE) requirements
https://ukcarglass.co.uk/windscreen-replacement
sngbarratt may be worth a look
Kind Regards,
Julie