Ok I hear this occasionally in my local supermarket played over the speakers. It is never loud enough and the tone is such that I can never fully articulate a single word/line of the lyrics with which to make an effective google/youtube search. I have never heard it anywhere else.
Solo female - pop - medium to slow pace - soundtrack has an 80s synth vibe to it, likely from the last 10 years though maybe quite recent.
This is what I think it sounds like she says in the chorusy bits. But could be wrong as google/youtube come up empty.
and I want and I want and I waaaaaant, Im a true believerrrrrrr
and I know and I know and I knowwwwww, Im a true believerrrr
With a oomphy synth Dun Duh D Duh D Duh D Duh D, repeat.