Definitely consultancies provides experience,re leaving letter as well as NOC too, but it depends on company and its policy, but any how one wants to have it ,no one should have issues to provide to ex employee for future support as an strong evidence of employement.
You may contact your company, they will provide it.
ISO Consulatnt & Lead Auditor
+91- 96707- 66 888
1st July 2013 From India, Lucknow