Just jumping in a bit here... evidence of work experience can also be offer letters, each year's IRAS summary statement (to show those are paid employment), and HR letter at the end of each employment to certify you in fact worked there, doing what, salary how much, and that you were an employee of good standing. If you didn't have a letter like that when you left your previous employment, you should be able to ask from the respective HR now. Just ask it in a sweetest and most charming manner usually does the trick. Haa!