How many ordinary people have any real way of knowing how secure any third party app provider is, though? These companies aren't big corporations, with well-established cyber security provisions, they are pretty small, perhaps even just one-man-band operations, so they cannot hope to have every security base covered. Even the big players sometimes get it wrong, as I found out with Google and my medical records being made public.
As for the time switch, I did say it worked for me, and that it was a time based solution, as per the title of this thread, not something to track a smart tariff, like Agile, which is way off-topic. Timing works perfectly for TOU tariffs, like E7. My charge points just turn on at the set start of the cheap rate period and off at the end of it, nothing much to go wrong, and as reliable as the metering system, which also just uses a time switch in the meter.