This must be incredibly annoying, signal issues have often been a problem in my location ever since I started (I gave up complaining a few years ago, although if I'm contacted offering me an upgrade I explain I don't want a new phone I want service, that is all). Does your phone have a wifi calling setting, as I understand it this can ferry texts as well as calls. Took me a while to realise this, and to realise it didnt involve annoying apps. I now have it on when at home only problem is wifi doesn't get into every corner of the house ,I do use wifi extenders but there's a limit to both sockets, range and sensibility. It's also no good when outdoors or away from wifi.
If you know this already apologies.
My work phone doesn't have wifi calling (even the wifi signal is terrible at my flat - it's a real black spot); I have a broken handset which I need to get fixed and then I can switch them but it's a massive pain. I got a big glut of texts yesterday lunchtime all at once and at least one had been sent two days before - that cost me a 90 minute booking with a nice bloke that I've seen before. I think people expect central London to be the place where everything works at the speed of light but a lot of it is horrendous
Still, I don't know that at least some of it isn't down to the punters phone since the other days this week have been normal enough. Half term this week, so likely a bit quieter which I won't mind too much tbh.