Fix grammar: I would like to drawn your attention to the fact that inspite of my several attempts to call your colleagues via mobile phone and land-line phone to check the device installed behind I moving into my new home, my request hasn't been responded until now, I am certain that by this simple and immediate step you'll be able to work out the reason of my increased costs.
I would like to draw your attention to the fact that in spite of several attempts to call your colleagues on mobile phone and land line numbers to ask them to check the device installed before I moved into my new home, my request hasn't been responded to yet, though I am certain that with this simple and immediate step you'll be able to work out the reason for my high bills.