stop payment on check

[maxtor]

i live in wisconsin and recently purchased a vehicle from a dealership in milwaukee and after my trade in the balanced owed on the vehicle was $1200.00.my girlfriend wrote out a check for the balance.the next day me and my girlfriend broke up and she put a stop payment on the check.now the dealership is threatining to contact the d.a. office.i would like to know if this is a criminal matter or civil matter?can i be charged with a crime?thank you for any info!