Fersal,
Look @ it this way. This is nothing against you.With the Technologies out there, do you think it is impossible to print out a "GENUINE" letter of employment, Letter of contract, letter of reference etc?.
There is a proverb in an African Language which says " To catch a Monkey you have to behave like one". What I mean by this is while you get your papers ready ask yourself the question, "Is this enough to prove". Put yourself in the shoes of the IO.
You are asking this question because you doubt it yourself. You fear that it might not be enough to prove, so the next step should be,
if I were u, what else do I have that can prove this.
Disclaimer:
This my personal view and experience.