On my small site http://www.mediadeals.co.uk , I am getting this strange error. The website was working perfectly well the other day around the old server.

The mistake is:

Fatal error: Cannot redeclare class soapclient in /home125b/sub013/sc71724-JPYM/www.mediadeals.co.united kingdom/www/includes/libs/payment/do_payment.php online 5261

I am sure it's related to server configurations. Does anybody understand what I have to do?

Coding is completely fine, without a doubt.

[cde] has become a built-at school in PHP. For those who have any scripts by using their class title you will need to change them.

i am speculating you've lately up-to-date to a different version of PHP. You most likely have to remove an include to something similar to nusoap.php because it clashes using the cleaning soap class within PHP5 and it is likely not needed any longer.