Podcasts never finish downloading - iPhone 4 dead end

I have an iPhone 4, which has been perfectly good for me up til now, but now the podcast app has decided it's not going to work any more.

I routinely get the behaviour of a podcast starting to download, getting to almost finished, then starting all over again, and then finally "unable to download this podcast" message.

It's extremely frustrating, and there is no apparent cure. I've reset, I've reloaded the app, turned on and off but nothing works!

I know that I'm now stuck on old IOS (iphone 4 not supported by IOS 8) but I'm not asking for new and exciting features to work, just the ones that worked until a short time ago. Really, really basic!