Downloaded albums disappear - again!

[JH11969]

This is becoming very annoying! Random times when I try to use Spotify in the car, all my downloaded albums disappear from my SD card. Sometimes they reappear when I'm next near wi-fi, other timesI have to download all over again. This can be time consuming as I must have 50+ albums on my phone. I am aware of this being a common issue with Spotify, but have to say - and agree with others - that as I am paying for a 'premium' service, this is something that should just not be happening.