Complex sentence: The pair spent most of it on clothes and hairstyling, then several months later Farian called them back and told them they had to lip sync to the prerecorded music or, per the contract, repay the advance in full.
Split into simpler sentences: The pair spent most of it on clothes and hairstyling. Several months later, Farian called them and told them they had to lip sync to some prerecorded music or, as stated in the contract, repay the advance in full.