Temporary Parking Permits

I bought some temporary parking permits from Brussels ths morning as my daughter is coming to visit. Thes are activated by sending a code to an SMS number. However, the commune office did not have any instuctions on how to use them, and they couldn't find the number...

They have promised to get this for me, but I've called them back several times and so far no luck.

Does anyone out there know the answer?

thanks

Peter