Offline Music disappears on restart

[Bstall14]

I have the device Huwaei Honor 7 16GB EU version on the three Network, i've tried different versions of Spotify and it still has this problem, i've tried everything such as emailing Spotify and after a while they gave me steps and i tried them and no luck! I have a big playlist over 450 songs and once i download them, if i restart device they are missing but they are still on the SD Card because i see it taking up the space. It's neither the SD Card which is 32 GB class 10 from samsung. I've tested other SD Cards and it still does it but if i store this songs interally it works perfectly? I've tried a test account from Spotify and still does the same. This is beyond a joke it's been happening a while and if this carries on i would like a full refund. It's good service just Offline never works for me, i've literally tryed every solution even tryed to reset my device and carries on, i have no apps which clean cache either so i don't have a clue, any tips/help would be appreciated a lot. ~Bstall14~