I believe there should find solution to this and look for a way to recover your private key even if anything happens to it.
There is a way. It's called backing up your wallet file or seed phrase. If you don't create proper back ups, then that's a problem with you, not bitcoin.
But the issue mentioned with how do you know that they don't just get the private key and then tell you that they couldn't resolve your problem?
If you know the address, then you can watch the coins to see if they are moved. If they are, you know the recovery company stole your keys. Good luck proving that to a judge though with zero other evidence.
i usually write it in the notepad and keep it as .rar files and set password for it
Don't do that. You already say you write it down on paper. Just do that. Storing seed phrases on any device with an internet connection is a huge risk. If your computer is corrupted, lost, stolen, damaged, whatever, and you cannot access your wallet file, then your electronically backed up seed phrase will be lost anyway.