At wits end. After 3 different support calls and 4 hours of support, NO ONE in support can fix what the upgrade broke. Can you help?

The question is: HOW CAN I ATTACH CASE(S) TO TRANSACTIONS, SPECIFICALLY JUST TO A BILL AND INVOICE?

I need step by step instructions because it used to work (prior to the 2007 upgrade). This is critical to our business. Is there any chance that they changed the custom CRM field. I think it used to allow me to filter on 'Type' and then do a compare and enter in a 'Value is'.

We have a vendor that makes repairs on our product. So, when I create a case for the repair, the CRM custom field on the case form ('AEM Bill') is blank. When the repair is completed and the vendor sends us a bill, I would enter the bill.