Please, I know the meaning of complain.
No, you still don't. Otherwise, you wouldn't have continued, defending a logically false argument.
1. Since the meaning of the word "complain" is to make a formal accusation, find fault with or express disagreement. Explain to me how do you warn someone before complaining first? What the hell would you be warning about?
2. The Americans have been complaining about Pakistan's role in Afghanistan since time immemorial (Trump cocaine-fueled anger and resentment wasn't the first, by any chance), my quick and simple question to you is if they are the ones dictating terms in that country and everything is being done as per their will, what are they complaining about?
3. How does it happen that Taliban still control a significant part of Afghanistan, despite the 100k strong ISAF (at its peak) spending trillions of dollar over a period spanning more than a decade now? Why is it that the US backed Afghan Govt has little power outside the capital city of Kabul?
4. If you disagree with the notion that Pakistan has been playing a significant role in Afghanistan or dictates terms there, how does it happen that the Russians and Chinese support and are willing to work with Islamabad over the Afghan problem - defined as a key regional player in the latest statement from the Kremlin's representative, than with Washington whose forces (noting that the International coalition is predominantly composed of US military) are actually present on the ground or Kabul which is actually whom they should be dealing with?
See, the logical fallacy, yet? Of all the things, I can repair or rectify, comprehension issues aren't one of them.