Vocal Voices

Me again! This is just a trivial thing but it's annoying. I have a little jigsaw app which whiles away a few idle moments. It's from Banda Games and I got it on Google Play for the Nexus. It has worked fine up until now, but suddenly it crashes when I try to download a new pack. I have done various things to see if I can fix it. The first thing I did was uninstall and reinstall it. That was the worst thing I could have done as it took me back to the original factory version and I lost all the packs I had paid for. There is a facility to "restore paid downloads" which just causes it to crash. It also crashes when I try to download a new pack, but it takes the money! Occasionally it will suddenly respond and restore a paid download, but there are still a couple of packs which it refuses to give me. Here are the things I've tried:

Uninstall and reinstall - no good.
Cleared cache in the app - made no difference.
Cleared cache in tablet - ditto
Downloaded Malwarebytes for tablet - didn't find anything wrong.
Ran AVG - didn't find anything wrong.
Installed Clean Master - nothing.
Installed the jigsaw app on son's Nexus 7. It worked perfectly on there, so I know it's something in my tablet that's wrong, not the app itself.

Any ideas? It's not a big deal but as I say, it's annoying.