Has anyone be competent to bring back a birth cirtificate from South Africa?

My son was born and registered in RSA but is English. We now live within England and as his certificate has been lost we have need of another one. I have applied to home affairs but no reply. I don't know his Id number, can anyone tell me how I could find his ID as this might help.
Answers:   
When you move to england, UK probably have a copy of his birth certificate. Ask the Hall of records or Immigration office for the copy.

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