have to re-download entire library! non-existent customer support

[calcio109]

I recently tried to contact a customer service representative going through Spotify's contact us-support algorithm, only to realize that there isn't an option to email anyone. Finally making my way through leads me to a chat where I posted the below question only to have the chat support specialist rudely end the conversation with me without providing any guidance or promise of further support... TWICE! I'm hoping someone here has some more insight or that a customer service rep can provide a response here. For additional clarification, most recent occurence was about 1 week ago on iOS 10.3.1 at the time:

"Have Spotify premium that I use mainly with iOS. Have a large collection of downloaded songs for use in offline mode, but in the past 2 years, on 4 separate occasions, my phone (both across an iPhone 6s and now an iPhone 7), has had to re download the entire library of saved songs (most recently approx 4500). This is, needless to say, incredibly annoying and a waste of my monthly cable internet data allowance. The first time I figured it was because I was approaching the storage limit of my iPhone, but this hasn't been the case the last 3 times (have 26GB of data left on this phone with last occurrence). I've tried searching your community forums or FAQs for answers/solutions and while several people and threads describe similar behavior, I can't seem to find a consensus answer. Perhaps, as is hinted on one thread, it has something to do with Spotify's offline track limit (I only today realized this is a thing, why does it even exist? and why is it a paltry 9,999 songs?), but again, I don't have that many offline songs on my phone. I also do not keep my device in offline mode, so I don't suspect it's a "failure to authorize" issue. Again, this behavior has occurred across multiple versions of iOS and Spotify, and across two iPhones, so I suspect it is intentional (overzealous reauthorization requirements? built into contract with music labels?), or a persistent bug in your software. Any clarity and solutions you could offer would be greatly appreciated as this problem has become increasingly burdensome. Thank you"