Fatal error HELP URGENT!!!?

[SOPHIELOVESYOU]

i ahve just purchased something on paypal and this has appeared..

Fatal error: Cannot redeclare class order_total in /var/www/osc-backups/www.****************.co.uk/ classes/ order_total.php on line 13

THE ***** are a website.
AND THERE IS NO SPACES IN THE LINK, ITS CHANGED IT AUTOMATICALLY WHEN IVE PASTED IT


PLEASE EXPLAIN CLEARLY,
IM ABIT STUPID WHEN IT COMES TO COMPUTERS

PLEASE HELP URGENTLY
IVE JUST PAYED £55 FOR SOMETHING, AND I DONT THINK ITS WORKED?

THANKS X