Ok, you should be able to create static routes to disable Google DNS.
Check your router's home page to see what your LAN address range is. (for example something like 192.168.1.1 - 192.168.1.255, with a mask of 255.255.255.0 would be typical, but yours might be different) You need to pick an address in this range that doesn't exist, e.g., something like 192.168.1.99)
Then enter a static route with:
Destination network address: 126.96.36.199
Subnet mask: 255.255.255.0
Gateway: 192.168.1.99 (or whatever non-existent LAN address you picked above)
Probably ok to leave on Interface as Auto, or pick LAN or LAN+wireless if you have to choose.
And repeat for 188.8.131.52.
This only blocks Google DNS. Then you still have to insert your unblock-us DNS addresses in the router's DNS fields.