If you want to charge fee for orders below a certain amount. (set in the admin) You need to change this line.

For example:

Surcharge Percentage: 2.50
Minimum Amount: 25
Payment Type: invoice


If the payment type is invoice and below the amount of 25 , then 2,50 is charged as fee.



Find This Line:

if ($amount > $this->minimum) {



Change into this:

if ($amount < $this->minimum) {

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