Alright, so here are my tests performed on separate days:
- Test €/CHF:
- Applied exchange rate (AE): 0.975
- Interbank rate (IB) at time of booking: 0.965
- Difference: ~1%
- Test €/CHF:
- AE rate: 0.978
- IB at time of booking: 0.967
- Difference: ~1%
In fact, the AE wasn‘t even traded in the past week. Don‘t know where they get that rate from but its definitely not the interbank rate. Haven‘t heard back yet.
EDIT: issue solved