Prestashop 1.4发布购物车更新(货币转换）

我在执行$cart->update（）时遇到了一个奇怪的问题更改货币后

例如，以英镑为单位，购物车的总金额为896.32当前的转换率138889（对欧元）

因此，以欧元计算，应该是896.32*1.388889=1244.89（四舍五入2）

但如果我在结账和支付模块上，我会：

$cookie->id_currency = 1; //1 for EUR
$cart->id_currency = $cookie->id_currency;
$cart->update();
//and then...
$amount = number_format($cart->getOrderTotal(true, 3), 2, '.', '');

它完全错了。。。最后的$total变量是错误的。

调试控制台：BEFORE$cart->update（）

$cart   Smarty_Variable Object (3)
->value = Cart Object (14)
   ->id = 2899
   ->id_address_delivery = "5"
   ->id_address_invoice = "5"
   ->id_currency = "3"
   ->id_customer = "3"
   ->id_guest = "998683"
   ->id_lang = "1"
   ->id_carrier = "14"
   ->recyclable = "1"
   ->gift = "0"
   ->gift_message = ""
   ->date_add = "2015-12-09 10:08:27"
   ->secure_key = "5b5c81dbecc7b7e1d9603752071321b7"
   ->date_upd = "2015-12-09 17:17:15"
->nocache = false
->scope = "Smarty root"

$total  Smarty_Variable Object (3)
->value = "£896.32"
->nocache = false
->scope = "Smarty root"

AFTER$cart->update（）

$cart   Smarty_Variable Object (3)
->value = Cart Object (14)
   ->id = 2899
   ->id_address_delivery = "5"
   ->id_address_invoice = "5"
   ->id_currency = 1
   ->id_customer = "3"
   ->id_guest = "998683"
   ->id_lang = "1"
   ->id_carrier = "14"
   ->recyclable = "1"
   ->gift = "0"
   ->gift_message = ""
   ->date_add = "2015-12-09 10:08:27"
   ->secure_key = "5b5c81dbecc7b7e1d9603752071321b7"
   ->date_upd = "2015-12-09 17:19:41"
->nocache = false
->scope = "Smarty root"
$total  Smarty_Variable Object (3)
->value = "1 239,67 €"
->nocache = false
->scope = "Smarty root"

正如您所看到的，1239,67€是错误的，应该是1244,89€

请问，错误在哪里？我要为此疯狂了。非常感谢你的帮助。