Exactly. I thought I was being clever using themes and plugins to build super fast... I don't know how to fix the plugins myself or rebuild them.
It's actually not just plugins but also the themes I'm using which add to the complexity. Honestly it's a total minefield and I think the solution is either to rebuild from scratch or just ask the clients to take over the hosting costs.
Really appreciate you trying to help - the world needs more humans like you!