Gutted to hear of your break in!!!!
  I hope you are luckly like me and find out through the grape vine who did it, just don't have any witnesses when you break his fingers one at a time like i did....it can get complicated!!!!! Not that i am in anyway suggesting violence is the way forward 
 
  I hope your wee man enjoys his day. 
 A quick thought to hopefully get the police out quicker. Phone them again and explain that your property is not secure and that your insurance company will not authorise repairs to make it secure until you have a crime reference number. 
 Ask them if they are going to be responsible should the scum return to finish off the job, seeing as it has been X amount of days since you reported it? Most forces are covered by Key performance indicators for response times, enquire about a complaints form to highlight their poor efforts on this occasion and they should sit up and take notice. 
 Sadly the chance of getting any forensics are fading as time goes on.....Insist on SOCO visiting to at least try and find something. 
 Good luck 
 Regards 
 ScottyB