Can't Install or Uninstall PTC Integrity Modeler!

I have PTC Integrity Modeler 8.3 installed on this work computer. I have a model made in PTC Integrity Modeler 8.5 and therefore cannot open it with 8.3. I want to install 8.5 well guess what!? Can't do that because it needs to uninstall 8.3 and for whatever reason can't find the IntegrityModeler8_3.msi file! And it doesn't exist on my computer! I also have no way of getting it. IT has also been unable to uninstall this program. So now this computer is essentially bricked in regards to Integrity! yay! I wish support would actually supply me with what 8.3 needs to uninstall itself, i.e. the .msi, or tell me what else I am suppose to do.