Curcy not working with discount rules plug in

Hi guys

I am having trouble getting the currency converter to sync with my discount plug in called “discount rules”

It does not take into account which currency the offer is in.

For example: Free t-shirt when you spend £30. And people have been checking out in there own currency which does not actually meet the £30 threshold in GBP but in their selected currency is is over the value 30 so it lets them proceed with the offer.

Any help is greatly appreciated:)

Thanks
Jack