firstly, I’d like to clarify if you are using Summary Disk Usage?
If so, you must specify both monthly and extra. Monthly and extra specify the charges for extra summary disk space. Extra and monthly for the rest 3 quotas (db, disk space & mail) must be left empty. This would allow the customer to increase these 3 quotas without being charged. But if the total space in all these 3 quotas exceeds the amount allocated as summary disk space, the customer would get charged
If you want to limit these 3 quotas, you should not use the summary disk space system. Uncheck that option and specify both mnonthly and extra rates for overages.
I appreciate you quick response, I still have 1 issue the registration form will not allow me to leave (db, disk space & mail) empty. Should they be set to 0?