Insurance and Memo

You see, my boy was born w a low birth rate and was denied (not approved) his insurance. Now that he is a big bigger, we reapplied for him again. And, the agent require a memo from his paeds of my boy growth. The thing is, we've been going to the local polyclinic for all the boy check-up, FU and vaccines. I called polyclinic earlier on and they mentioned they dont do such memo for insurance purpose and advise me to go to a private GP. Anyone facing issue like this? Can i just go to a GP to get a memo even when they have no records of my son? Anyone who works at a GP care to share? Please refrain comments like asking me to call GP. Thank you in advance.