It's not necessarily correct that text messages can't be used in evidence.It depends what they are being used to prove or show.They may be to prove admissions or confessions or inconsistency or serve many another purpose, the law of evidence permitting (and there are whole books on that).Even if not permitted by that they may lead to other evidence which can be used, which the solicitor may find.And, in civil cases, the rules about hearsay are so generous that virtually anything which might be excluded in a criminal trial, as hearsay and not an exception to the rules against it, or excluded as unfairly prejudicial, can be admitted in evidence