Do you already run an audit on your phone to look for a potential malware? There’s a lot of same issue like you with Coinomi especially wallet with huge amount of Bitcoin that dormant on there wallet but since Coinomi is a non-custodial wallet, its very hard to accused them stealing your money since you are the holding your private key. Jut follow there suggestion to report this to law enforcement so that they can easily request files the company that received your Bitcoin.
Invest on hardware wallet like trezor and ledger next time if you are holding huge amount of Bitcoin to a none open source wallet. Sorry for your loss mate.
The law enforcement don't work where I am from east europe.
I don't accuse them of stealing but something is shady
the bitcoin was moved after the update , ~3years was all fine if somebody have the seed they they took it at that time when they get it not after some time.
This happend after the update, somehow the seed was send out from the wallet.
I scan the phone with Malwarebytes no issues.

I do have a ledger but not I don't have coins to put on it .
I totally understand your point since the fund was safe for over 3 years of being dormant. If you are sure that you didn't browse any malicious website before the hacking event then Coinomi system has some bug on there update which we can't verify since they are not an open source code. The best thing to do is to gather all the complainants in different forum and social media outlet to raise concern to Coinomi, The way they are using there Company as answer to your complaint is a bit shady for me. They should give you a technical investigation report to prove that there system has no bug for a potential leak of data.