I should say I paid 6am Swiss time on the 16th January 2015.
I called them.
1. There is a form on the swisscard.ch web site to fill in, print sign and send by post if you have any complaint about the bill from 30 days of getting the bill. After 30 days they consider the bill final.
So I filled that in.
2. Speaking to them the date of purchase is not the date the exchange rate is taken for the exchange it is some time afterwards. In my case this was the 18th January a Sunday.
3. There are some pdf's for each day (on swisscard.ch) including Saturday and Sunday with all the exchange rate information on them. I dug up the one for the 16th of January and the Euro was still worth 1.2 CHF. The day after the Swiss franc had increase in value.
I think they are in a big mess.
I pointed out to them in a letter along with print outs of their exchange rates and the one's from mastercard.
1. Their exchange rates for the 16th January reflect the exchange rates before the CHF rose at least 10%.
2. According to the bill my exchange rate was calculated on Sunday 18th January. The swisscard web site has a much better exchange rate on this day than I was given.
3. Why do they take exchange rates on a Sunday a non banking day. Surely a better day would be Monday for all weekend transactions.
I don't know if anyone has any answers for any of this.