I was going to say, you don't need a DIY store, you need a camping/outdoors store and to get a survival wire saw. With those things you can fell a small to medium tree, and have it cut up in next to no time with one of them. They come in long enough for either one person or double length for two people but the OB saw wire is the same idea.

Like you probably found out, speed is your enemy with those saws. You need to keep them moving slow and steady so they don't get too hot, otherwise they stick- whether it be the sap of a tree or the glue on the wall!