D0oin no argument or issue with what you're saying. However, just thought I'd contribute that when i got my dog from Dogs Trust I had the 'talk' which was fascinating, comprehensive and very very much in line with so much I've read on here re positive reinforcement etc.
However, although the Dogs Trust talk lady said quite vaguely that she might take a while to respond if we left her a message, there was nothing in the pack that gave me her phone number. There was no mention in the talk or in the pack I brought home about ongoing support and the pack certainly didn't contain her phone number! There was no mention at all of commitment to back up or behavioural support, there were no phone numbers for this. To be honest, all there was was in the pack was a lot of advertising. I have no issue with that at all, but my experience of a major rehoming charity doesn't quite match what you're saying.
Now, if I were to call them and say I had a problem that might be different, but there is nothing I have been told/literature I have been given that would make me think help would be available so I wouldn't think to call to be honest.
I have needed a lot of help with my dog and still do. I have got it via the internet, books, other dogs owners and on this forum. I suspect that is probably fine, but it's not quite what I read on here about proactive ongoing support from rehoming charities.