There's really nothing to be done by yourself since you didn't archive... unless... you perhaps backed up your hard disk before going to 7.2 (c).
I note you're a current customer(4), and you've been a member for almost 3 years. Were I you, I'd write to email@example.com to see if they can help you.
There are one or two tricks you might not have tried...
1. Open Impulse and under "My Software" single click on WB7 and them press "Shift + right click". A submenu should appear. Choose "Verify Installation". If the choice isn't there, close the submenu that did appera and try again.. shift and right click. This should either give you (after it's run) WB& correctly or incorrectly installed. If "Correctly installed" then go to 2. If not (and I'm betting on this) then do the update and reboot.
If WB7 was correctly installed:
2. In Impulse -> Preferences and under general, untick pre-release versions if it's ticked, and then click OK and close Impulse. Then restart Impulse and it should show an update for WB7. Update it and it should revert you to the prior released version of WB, after reboot.