OSX seems to set 802.11d country code upon the first found network's country code. This might not be the correct one, depending on your or your neighbors' settings. This script restarts your Wi-Fi until (or 10 times) the correct country code is set.

gistfile1.applescript

-- This does not work if you need administrator privilieges for setting Wi-Fi power
set correctcountrycode to "DE"
repeat 10 times
	set countrycode to do shell script "system_profiler SPAirPortDataType -xml | xmllint --dropdtd - | xpath '//key[text()=\"spairport_wireless_country_code\"]/following-sibling::string[1]/text()'"
	if countrycode = correctcountrycode then exit repeat
	do shell script "networksetup -setairportpower en1 off"
	delay 6
	do shell script "networksetup -setairportpower en1 on"
	delay 2
end repeat

Does not work on Mountain Lion

this works in Mountain Lion - I switched correct country code for bad one, as my cosmopolitan neighbourhood has a friendly DE router and bane-of-my-existence TW router, which invariably gets picked up by airport and takes out my 5ghz channels.

# Bad Country Code
set badcountrycode to "TW"

# Fetch the name of your AirPort Device
set airPortDevice to do shell script "/usr/sbin/networksetup -listallhardwareports | awk '{if($3==\"Wi-Fi\"){getline;print}}' | awk '{print $2}'"

repeat 10 times
    set countrycode to do shell script "system_profiler SPAirPortDataType | egrep -m 1 'Country Code:.[A-Z][A-Z]' | cut -f2 -d: | cut -f2 -d' '"
if countrycode ≠ badcountrycode then exit repeat
toggleWifi("off", airPortDevice)
delay 6
toggleWifi("on", airPortDevice)
delay 2
end repeat

on toggleWifi(value, device)
        do shell script ("/usr/sbin/networksetup -setairportpower " & device & " " & value)
end toggleWifi