SIM card

Hello,
I have an All-in-One contract with you since the end of August. On the 11th September I signed a contract for O2 Free S Partnerkarte mit 1 GB, for my son. It was denied. I claimed again on the 13rd and it was denied again (I still don't know on what grounds). Finally on the 14th it was accepted (via email) and I was told that I would get my SIM card by post. 11 days have passed by and still no sign of the SIM card, and my son had to leave on a school trip without mobile. Could you please explain the situation to me? I don't understand why to begin with I couldn't buy a second SIM card and now why it is getting so long to get one. I should have bought it in another telephone company and have it on the spot.
Thanks.