I’m not at all clear on your precise issue so can only speak in general terms.
Lawyers, particularly Barristers, do provide written Opinions all the time on legal issues. You will pay heavily for such an Opinion, depending on the complexity of the issue involved.
Such Opinions however are usually for the benefit of the individual client only, and not for wider circulation. Accordingly, whilst any Opinion might give you some comfort, it may not provide comfort to your customers.
If you were instructing a lawyer to prepare an Opinion, it would be important that you advise them them for what purpose the Opinion is being used. Any such Opinion will be heavily caveated, for example, that it “is for the sole use of the client, and not to be more widely circulated or relied upon by third parties...” etc.
On the other hand, if you instruct a Solicitor to represent you in forthcoming potential or actual litigation, it is absolute standard practice for Solicitors to issue denials on your behalf to accusations and to demand that the other side provide evidence of wrongdoing. Such correspondence will not usually persuade the opposing party (or customers) that there is no case against you.