Time Block Tracking

Greetings!
I am developing a site that sells Time Blocks to clients for services, I was curious if there was a plugin available that would be of use for this.

We are using eshop to sell the time blocks.
What we would like to do is this:
Once a block of time is purchased, allow employees to “clock in/out” on certain blocks of time and alert the customers what work was done, how much of their time block was used, and how much of their time block remains.

Any thought?
Thanks!