2nd Brew and I'm stuck

Well I hope I'm not stuck. I started a nut brown ale on 5/3/09 and all seemed to go well. The estimated O.G. was 1.062 and I ended up at 1.061 sweet. I pitched a 11.5 g packet of safale s-04 and laid it to rest. There was airlock activity in less than a day and everything seemed to be going well. I let it sit until 5/13/09 it started dropping in temperature to the mid to low 60's so I moved it to a warmer place after a gravity reading 1.018. It warmed up and the airlock showed some more activity. I went away came back and checked it on 5/20/09 and got the same gravity 1.018. So i swirled it and waited till today and the reading is still the same. Now what do I do? I have a small 5 g packet of munton's yeast and some more s-04 do I repitch or just bottle? I was hoping to get the gravity down around 1.011 or 1.012. Thanks in advance for the help

One question I have for you would be was this an extract recipe or an AG. If it was AG, then mash temps may have been a little high creating more unfermentable sugars.
If it was extract, then it "should" have finished out closer to the expected FG.
Recipe info and procedure would be a little more help.

It was a extract kit. The ingredients are:
8 lbs Ultralight(boiled for 60 mins), Steeping grains(held at 155 for 30 mins 8 oz Crystal 60l 8 oz Caravienne 4 oz Victory & 4 oz Chocolate. The hops were 1oz of Northern brewer(60 mins), 1 oz Willamette(5 mins), 1 oz Willamette(1min) I also added whirfloc with 10 minutes left in boil. I did a full boil and pitched the yeast at 72 degrees. And it was fermenting just under 70 then the temp dropped and I moved it and it got back up to 70 but it seemed to late