Other AV companies provide a simpler approach for submission of files. For instance Norton provides a portal namely submit.norton.com . Please check this portal for once and try to introduce similar portal for users. In short by using this portal Norton users can submit suspected files or files which exists on virustotal. And soon within 2 or 3 days a detection is added for it.
That portal of norton even provides an option to submit 256 hash or MD5 hases.
So if possible try to introduce similar concept for Trend Micro. Kaspersky has Opentip portal of itself. All I want is provide a simpler approach for file submission.
It takes days for getting a file reclassified this way. You can continue providing existing option as well for detailed and specific assistance for customers. But if possible provide a website similar to Norton submission portal or Kaspersky's Opentip.