customer service upgrades and app issues

i bought this subscription originally when the app first came out for £2. recently for reasons i had to make a new spotify and repurchase the lifetime subscription (which is fine). the app acknowledged the purchase said i had premium. the premium didn’t work. the email support told me to contact apple and not them. which i did, i informed the customer service agent that apple said the purchase went through fine and they’re not responsible for 3rd party apps which is what i assumed and makes sense. the only thing apple could do would be to offer a refund if i applied that it didn’t work as advertised. before doing that i told the customer service agent for stats fm and they said to do it. essentially telling me to just not use the product. very disappointed as this used to be my favourite app which i recommended to everyone.