Hello there Zcorpy,
a little more detailed information might be needed to help you in this particular case if you wish to continue using the vanilla client. If you change to OTClient you won't have this problem anymore.
As far as I know the magic level is saved in the client either as an unsigned char (which values go from 0 to 255) or an unsigned short (which goes from 0 to 65,535) so the max value cannot be 156. You might consider checking the sources of your server first....
Regards,
Okke