David Banks usually do not give any more precise information about why they don't accept certain customers, otherwise it would make it easier to undermine their requirements or to cheat their verification systems. Not saying that you in particular would be doing something like this, just that this is a reason for why more specific information about requirements are generally not given out to the public.
There's not much one can do except try to open an account at another bank. In most EU countries, some or all banks are required to offer basic accounts that can be opened by anyone. So even if you're facing acceptance problems with multiple banks, you should always be able to get such a bank account. In the case of The Netherlands, this is not a requirement for all banks, so bunq does not offer basic accounts.
There is one competitor that does, but the opening process is definitely more complicated than for normal accounts.
