Mgmgmahn

I had been working for a computer manufacturing company (...) for nearly
2 years as a core C# programmer. But I was not an employee. I worked as
a a full-time contractor (40hrs / week).
It has a rule not to give a professional reference with their letter
head to any contractor. How can I prove my professional reference for
these periods working as a full-time contractor?
I can give my Project Manger's name, designation, email and phone no.
(work and mobile).
Pls adivse me.
Thanks and regards,