Creating Timer and AHT calculator

Good Day Everyone,

Hello to each and everyone of you here, currently I am in a middle of a project that would create a stop timer and at the same time will calculate automatically the time that they have spent on a call , so far I have 5 buttons.

Start : giving the hint that the call have started
Hold : when they place the call on hold ( in the code that I have it is not accumulating the time when I click the hold and it click it again to go back to the call I wanted it to accumulate with the Talk time same goes for the ACW button when I click it)
ACW : when doing this I wanted it to accumulate as well with Talk Time and Hold Time.
Stop: to totally end the timer
New Call: I wanted it to be automatically goes to the new row below the first one and then increment everytime I click the button and round robin with the codes that we have .

I hope some one can help me with this.

Thanks in advance.