I remember the days when we had to supply our own entertainment…a radio with a powerpack was the norm in cars…but in my maudsley i had to fit an 8 track, then when i got promoted to a thames trader, took it with me, well that was till the cassettes player came about…whats all this with a cd, i thought thats what you needed to get a job…how times have changed 
Anyway, until recently, my car had a Cd player and cassette ( all in one ) with multi changer ( held 12 ) but since i changed cars i only have a cd, but it does play mp3 so thats all good but sadly no multi changer.
I think your boss is being mean fisted by going for the cheapest option of a bare basic radio, with no cd player. as for paying £10 a month for spotify, no thanks ill continue downloading and putting it onto cds that i can take in the truck and the car, and even from youtube as well..illegal or not, but i literally have hundreds of cds full of the music i love.