Nobody Got Any Advice Of To What I Can Do? Awww Well It Was Worth A Try

hi my first post so be kind haha...... I would like a bit advice about claiming PPI back of ( Hadenglen Plc ). It was back in 2003 and ive read that Hadenglen was not pre-regulated before 2004! so dont know where to start or to who i sent my claim to? it was a single premium of £1,379 and was added to my mortgage with ( Platform ). So what chance have i got of getting anything back and like i said who do i sent my claim to. I still have all my documents and insurance certificate in which that was with ( Millennium Insurance ). Confused!!!!! thank you in advance to everyone....