I would concur with you that the example sentence is not felicitously constructed, even though it would probably pass muster at least for conversational purposes.
The most basic function of the past perfect is, of course, to denote an event chronologically antecedent to another (main) event. Thus, while we might logically expect
They HAD BEEN given help and advice before they MADE the decision.
on the basis that the advice patently preceded the decision-making,
to reverse the tenses seems on the face of it to be at best a redundancy, and at worst a blatant misuse.
However, as illogical or unnecessary as it may seem, the use of the past perfect following 'before' is so widespread among natives (He interrupted me before I'd finished speaking, etc.) that it is difficult to account it an actual error.
Personally, however, I would be loath to recommend this usage to learners and believe that the best solution in such a case is usually the most minimalistic, to wit
They WERE given help and advice before they MADE the decision.
relying entirely on common sense/the wording itself to determine the sequence of events, reserving past perfects for the relatively small minority of cases where common sense alone is not sufficient to determine the order, e.g.
They let me sit at the front because I HAD BOUGHT a special ticket.
indicating that the second action in this case took place before, and not after, the first.
I hope that this answer is of some help!