I have made a small change to the script designed by "wagen".
1. Different url to receive the xml file
2. Changed
$GBP_EUR = round(1 /$exchrate[GBP], 8);
into
$GBP_EUR = round(1 * $exchrate[GBP], 8);
and
$GBP_USD = round(GBP_EUR *$exchrate[USD], 8);
into
$GBP_USD = round(1 * $exchrate[USD], 8);
3. Changed tep_db_query("update currencies set value = ". $GBP_EUR ." where code = 'EUR'");
into
tep_db_query("update currencies set value = ". $GBP_EUR ." where code = 'GBP'");


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