Hi
Like mentioned above you need to prove with Statement from Bank, letter from finance section, or pay slips etc that the job is paid. Alone exp certificate doesnt do. Sorry about it. But 3111 would be in next year line up, so please be ready to re- aplply.
Try contacting CIO as well for an explanation and appeal. Though there is no such procedure but you have nothing to loose.
I think experience letter alone might be the reason for rejection. At the least, job contract also had to be submitted and a business card of the person who signed your experience letter. This requirement was there in visa office specific instructions for Pakistani applicants. Thanks
