When you get Khor. Ror. 22 certificate in thailand does it run out after a month 3 months year does anyone now

Hello, I was wondering if anyone has had delays receiving the Residency Certificate? I went to Immigration on 29th March and I still haven't received it in the post. The process is currently that we pay 10b for a stamp addressed envelope which I did but I didn't get given a ticket or any form of receipt. I need to receive it as soon as possible. Thank you in advance.