double payment via phone

[Ellipih]

I've just gotten to the conclusion that i've both been paying for my spotify by myself through my visa card, as through my cellphone company. 

Somewhere in either november or december I came to the conclusion that i no longer had premium after having had it through my cellphone company for about a year, so I logged in to the website and added payment information to pay for it directly.

Now I've put the cellphone on my name, and I've come to the conclusion that Base (the cellphone company) was still charging me for spotify?! So basically I've been paying double for about half a year. 
Right now I've cancelled the option through my cellphone company and am keeping an eye on what will happen to my premium account because I am still paying through my visa card. 

But now I'm wondering how spotify didn't notice that it was receiving 2 payments for the same account with the same phone number and why it didn't notify me about this?