I'm not sure it is
this one or not or how much info they get but Bet365 has a passport scan verification. They don't even need to scan it, just the code on the bottom of your passport is enough.
Not entirely sure how they have access to that, but FSA licensed institutions in the UK including PayPal, Skrill and NETELLER have a super advanced one. For the FSA ones when code is entered it pulls up the actual passport. So if one person is holding looks different it is spotted right away. Those ones often also get information on other passports that are already linked, for example are a dual citizen and multiple passport ownership has been detected, and also use facial recognition to search for other matches.
Them saying it is not you is concerning. I'm actually surprised they told you that though.
For right now as much as it sucks I'd say just be patient. If all is legit you got unlucky. They are not in the business of stealing, there is something about your ID that raised a flag. Depending on what the flag is, there are plenty of reasons it might take a little while to work out.
If we get to the point a week has passed since your last action and it is at a standstill then report back for new ideas.