When currencyformat is set to EUR, it is not currently possible to enter amounts into pay amount /cgi-bin/koha/members/paycollect.pl?borrowernumber=XXX using ','(comma) instead of '.' (point).
Duplicate of Bug 12310 ?
*** This bug has been marked as a duplicate of bug 12310 ***
*** This bug has been marked as a duplicate of bug 19521 ***