Tell him you want more money.  Ha ha.  No, you prob have to follow it but can still add some standard esl games at the end or a couple of times a week or something. 

Teach what is in the book but make it more interesting. Make interesting ppts, interesting activites to learn the vocabulary and phrases, add fun games, and don't be afraid to expand on lessons, if you deem it appropriate. If your running out of time or ideas, you always have the book to fall back on with minimal prep work so it will help you out.

This is what I’d usually do but boss said to follow books exactly and don’t add games, it’s hard to keep 6 year olds focused without adding anything fun haha

That really is rough because keeping 6 years olds entertained period is tough. I would suggest being really animated in your teaching and doing things like using funny voices or incorporating a lot of movement, dances, funny gestures and faces, etc... if you can't add anything to the material. I know it sounds silly but I find with the younger kids, the sillier the better. You may run into a problem with them thinking you are their playmate if you do it too much but if fun is what you are after, I have found this to be very effective.  Good luck!