Music problems that arose

We wanted to use the instrumental of Kesha's song - ''Tick tock'' however we cannot use a signed established artist but if we do we need to get permission so we went on the website to call her manager. We decided not to call as our media teacher told us that there is absolutely no point as we wont be allowed to use the song for our instrumental and if we was then we would've had to pay a huge amount of money.  So we are just going to make our own music via garage band and use similar sort of beats to conform to the chick flick convention.