So, suppose that you're starting your favorite server with a couple of friends/strangers/mortal enemies (Basically, the number of people on the server is 4 on 4 or less). Anyway, you've been doing well K/D-wise, maybe even picking up a domination or two when all of a sudden some of your opponents get frustrated and turn to the dark side.
They go heavy-medic.
Now what? The main counters to such an atrocity are sniper/spy, and both are much less effective when there's only a handful of players on the server (because there's less distractions, enabling the enemies to focus on disrupting the support classes).
Since almost nothing will beat that kind of firepower at close range, your only hope is to use hit and run tactics, and try to take out the medic. However, considering that the medic will try to hide behind his 450 health buddy, has his own healing factor, and will likely flee to a health pack given enough time, you'll likely have to try and take him out in one shot. Which will usually leave you shredded by the heavy. And even if you do get close to managing it, the medic uses an uber, and you're foiled anyway.
Is there an effective way to dismantle this combo without sinking to their level and using your own cheap tactics? (ie: Your own heavy medic combo, stickybomb trapping a doorframe, etc.)