hello my sitemap appears to not be accepted by google for indexing could someone help me with this? see image attatched

You would need to get more information from them on this. From what I can see there, it doesnt seem to be its not accepted, but rather it cannot get to it. 

yeah but thought maybe its invision issue that it cant be accessed but ill contact them 

@Marcis there a way i can make the sitemap a xml instead of php?

There is no way in which to change this, no

It could be your robots.txt although you would need to clear the system caches and if applicable the CDN cache as well before testing
Try the recommended robots.txt

i use the invision recommended robots.txt so i cant really imagine that would be the issue since that would mean anyone that uses that cant use their sitemap

Its accessible from what I can see. My best guess would be that your hosting is blocking google from accessing that page. The message itself doenst give you much, but it does seem to indicate it cannot get to it at all.