Support: Problems creating reports

Hello,
I've been testing the simpleinvoices for the last week now and everything seems very reliable and simple, overall it looks absolutely great!

However, I did encounter a problem which i've been trying to tackle for quite a while now. For some reason, the reports do not work. I asked my server (or how do you call such person/company) if they knew anything. They didnt really, however, they did tell me it wasn't possible to set the chmod to 777, but to use 775 instead.
Secondly, while browsing the forum a constantly saw stuff involving changing php.ini, where could I find such a file? (i am starting to believe that changing something in this file isnt really in my power, but should be done by the server as well).

So, to summarize, I would really like the reports to work, I think I made the /tmp directory writeble. The server is running linux 2.5, apache 2.2, mysql 5 and php 5.2

What can or should I do???

Thanks in advance,
king regards, Sjaak Schukking

To be precize, it states:

Warning: fopen() [function.fopen]: SAFE MODE Restriction in effect. The script whose uid is 86371 is not allowed to access /tmp owned by uid 0 in /storage/mijndomein/users/030364/public/sites/www.penfields.eu/invoices/modules/reports/php/PHPReportPage.php on line 223

Warning: fopen(/tmp/phprptGoDbYZ.xml) [function.fopen]: failed to open stream: No such file or directory in /storage/mijndomein/users/030364/public/sites/www.penfields.eu/invoices/modules/reports/php/PHPReportPage.php on line 223

ERROR!
PHPReports could not create the XML file with your data to make your report runs. Please check if the web server user have rights to write in your temporary directory. Script aborted.