extra fees dependant on the checkout method you use

I am trying to implement fees in my checkout based on the payment gateway i select. I have implemented this via this plugin (https://en-gb.wordpress.org/plugins/checkout-fees-for-woocommerce/) but it is not updating when i switch currencies. eg i have a added a fixed fee of £4 and an additional fee which is 2% of The total cart price. This fee will only show when i select cash on delivery in the checkout. My default currency is GBP and it shows fine but when i change to sar, usd etc it doesnt change based on the exchange rates set. it just shows the same price as GBP. the plugin works but i cant put the plugin live as the fees are not changing currency.