More My Book Live 3TB speed issues with Time Machine

After buying My Book Live 3TB to use as Time Machine for 1TB iMac and 1.5TB external drive I tried to do the initial back up wirelessly as advised with the instructions. After 16 days it hjad still only backed up 2TB of the 2.37TB 

I then tried to back up with direct ethernet connection to the iMac. My Book Live backed up the first 1TB in a matter of hours but has since taken more than two days to get from 1TB progress to 1.6TB progress so at this rate the back up will take almost another three days to complete.

I had connected as Guest because My Book Live would not accept my admin name and password combination and this attempt at backing up failed without completing.

I am now logged in to My Book Live using password and trying the third back up, but this time I didn’t include the external drive in the back up. It is now day three and My Book Live has only backed up 128GB of the 958GB. 

Help!

Check the link below for some advice on how to improve your transfer speed. 

http://wdc.custhelp.com/app/answers/detail/a_id/5736/session/L3RpbWUvMTM1NzE2MzMzNi9zaWQvSGcyaklqZmw%3D