Busta Rhymes has been burning up the phone lines so much, he apparently racked up a $9,000 bill. A spy said the rapper had a downtown AT&T store tied up dealing with the outrageous bill Friday afternoon. One shopper tells us a frantic customer-service rep was glued to the phone trying to sort out the humongous tab. The source said the “Pass the Courvoisier” star has been racking up the minutes rapping on the phone for the past three months. Rhymes’ rep said, “No comment.”