What's 15' snake gonna do for you?
You probably should of pulled the trap off the sink (assuming a sink backed up) and snaked the arm over with a hand crank
The problem was a slow flushing toilet. It was not stopped up, just bubbling when flushed. Bought a 25' snake that operates with a cordless drill and it grabbed the other snake on the first try. Then I ran the new snake down and cleared the vent. The toilet works better than ever.