Thanks for getting in touch with us!
I'm sorry to hear you feel this way! If you're within the UK, and making calls to Vietnam - which is within Band 7 of our country banding list, you're correct that the cost of the call will be £2 per minute.
I completely understand that the usage from mobile to mobile calls can be deducted from your bundle allowance, if not free, however, this is only the case when calling within the UK or within the EU, on our new Roam Like At Home plans.
If you're calling a foreign number outside of the EU, this is classed as an international call and therefore, does come with a cost of £2 per minute - regardless of mobile to mobile, or mobile to landline connection.
You can check out all of our roaming charges over at - https://www.plus.net/help/mobile/roaming-and-international-calls/.