Change from ESR to ESR+
Fixing wrong ESR coding line: last digits must be only 9 chars in total (with the esr-code and the checksum), not only the ESR-number in the middle
Moved the address a little bit upwards on the invoice slip
Enable 'Enter' and 'Return' as accept key in the amount box and not only return
Fix the query for remind all who have not paid for a given amount of months; Change variable name and enum to be more logical