Nokia 6236i reception problem

I bought my 6236 a couple of months ago and I was quite happy with it. But recently I started having horrible reception and poor battery life. The problems started two weeks ago when I changed my office. I normally let the phone run down and then charge it overnight. It lasted about two or three days and I talk really a lot. But now it’s not like this. I know that the building can cause the problem with the reception, but what about the battery life? I was given a replacement, but it has the same problems. Can anyone suggest what is wrong?

Yes, definitely the building is most likely to cause the problem with the reception. As for the battery life it results from the bad reception as when the reception is bad, the phone needs more energy to lock onto a signal.