It looks like line 157 is out of sync.
It has:
$MotleyCart->AddToCart($ATC_AddIfIn, $ATC_RedirectIfIn, $ATC_itemID, $ATC_itemName, $ATC_itemDescription, $ATC_itemThumbnail, $ATC_itemWeight, $ATC_itemQuantity, $ATC_itemPrice, $ATC_itemColour, $ATC_itemReturnLink);
it should be:
$MotleyCart->AddToCart($ATC_AddIfIn, $ATC_RedirectIfIn, $ATC_itemID, $ATC_itemName, $ATC_itemDescription, $ATC_itemThumbnail, $ATC_itemWeight, $ATC_itemQuantity, $ATC_itemPrice, $ATC_itemColour, $ATC_itemSKU, $ATC_itemReturnLink);