Unable to do anything on mobile banking on Sundays

On Sunday, I needed to transact whilst in a store, but the systems were offline and I was unable to shift credit between my budget and straight facilities, in order to allow me to tap my virtual card (as this only allows for straight transactions). When I phoned the Private Wealth service desk, the consultant informed me that the systems are offline and when I enquired thereon, I was told that "Sundays are not banking days". However I find the need for maintenance necessary, it would be quite helpful to be informed in advance of such downtimes, and not just get a response that Sundays are not banking days, as I was in need of making a purchase at this time, which I was eventually able to make after borrowing some funds from other sources. I appreciate that Sundays are not banking days, but also it is not as if I required any huge service, it was literally shifting a threshold between straight and budget.