Hi Kok Yong,
I created a field as Number field and I set the property "Number of decimal places" to 0.
When I export my values to Excel I don't get any decimal point there, the numbers show up as I entered them when I created the list items.
Please ask the customer to do the same.
Also,please check with the customer whether he has some Excel setting in place that would force to see numbers with decimals.