National Auto Glass not to be trusted

Good Day,

I submitted a windscreen claim on Monday 12 March 2018. I was then advised that National Auto Glass would contact me in order to fix my windscreen. National Auto Glass then contacted me and told me that my windscreen would be fixed in 3 to 4 working days. It has now been 2 weeks and my windscreen as not been fixed. I have been calling both Outsurance and National Auto Glass but no one has given me feedback and the crack on my windscreen is worsening. I have been following up with both National Auto Glass and Outsurance, but I still have not been given indication as to when my windscreen will be fixed, even though I've been highlighting that the crack is worsening, thus making the fixture urgent.