Help------ -dumpprivkey gives key connected to different address
You can install a lightweight wallet to your phone, this will work much faster than since it doesn't need to download the full blockchain and verify it.
Then you can import the private key and you will be able to use your bitcoins.

Some options:


electrum.org
exodus.io
Mycelium
GreenAddress


Not all of them support all operating systems but together they cover Windows, Mac, Linux, Android and iOS.