The error 921 is an issue with the apk that are being fixed, in the meantime you can use this alternative app, using downloader pop in the url below to download and then use your service login details.
The original apk will be fixed asap!
We had an a slight issue with the new payment processor for all American Express customers.
For some reason the payment descriptor was saying "IDEAL" instead of "Universal "
This is now fixed and in future will appear on your statements properly.
If you see the IDEAL on your statement that is us