How much you have saved compared to what ?Lloyds bank exchange rate , post office currency rate, CC rate ? I think it would be a bit meaningless because Lloyds for example charge £1 per transaction whatever the amount + 2.99% of the transaction amount, if I had 20 transactions of £10 in a bar I would save a fortune, if I had 1 transaction in a bar of £200 - id still be drunk , but would have saved £19 on transaction fees, if I had used a Halifax CC Id have saved the transaction fees but wouldn’t have known for a month until my next paper statement how much it had cost to get drunk - If I had used Mondo Id still be drunk but paid no fees to get there and known straight away- well until at least half way through the night ! . NOT THAT I DRINK A LOT 
- If possible Id like the top up amount to be displayed in local currency and GBP so I know how much I have to top up to cover a bill - however will we still need top ups when you are a bank and its a main account …hmmmm