Guys, not sure about WES but an year ago i reviewed this document about how IQAS assesses various credentials. Basis that I went ahead and opted for 1 year PGDIS course from IGNOU. Will be completing the course this year and then will have it assessed. In the meantime, this document might give you some idea and hope...
https://www.alberta.ca/documents/IQAS/india-detailed-credential-templates.pdf
Refer Page 46, 56 for Post Graduate Diploma (duration ranging 6 months to 2 years).. It says 1 year PG Diploma is generally compared to PG Certificate. If that is true, then also it will gain extra points for "Two and more degree, certificates...".. Will solve the purpose.