The only mail order company I ever use is Fosters of Birmingham, not sure whether they advertise on FM but Ive never purchased any tackle on line.
I use Fosters because of the good service and they were recommended not because of any advertisement.
To be honest having spent a small fortune on small adds in free papers/directory's I often wondered whether this type of advertising benefits anyone but the company displaying the adverts. At times the cost was greater than a weekly income
As you say Mr, C, word of mouth/recommendations is/are far better, at least for a small business/sole trader