Lawn problems....lumps and uneven?

I have a question...I built a house back in 2007. Well, we sodded Bermuda gr, but the company that leveled the yard off and all didn't do a very good job. I was hoping that the gr would level out over the year last year but it didn't. So, my question is, what can I do to level it off? I was going to see about rolling the yard, but have heard that it isn't good to roll after sod is placed....especially a year later. So, what can I do to level and even the yard out. I just want the lumps out of it so that it will make a nice even cut and pretty lawn. Thanks