I find this sort of scam is frequently a favourite of Irish crooks who could be involved in burglaries too. I have had a fake BT rep call here but when I heard the Irish accent I told him I dont have a phone.
Another con they use is to pretend to be painters and decorators where the idea is to get inside the premises and case it with a view to burgling you. A friend of mine had these fake decorators call around. They had Irish accents and were fakes.