cause i am utterly annoyed with them aka matt minor sold me a crap S2 lsd box for my FRST which was supposed to be reconned which it wasn't and broke within 24 hrs

which i paid £275 for
he assured me the box has a 28 day guarentee, rang him told him its broke he told me he'll come get the box and give me my cash back ...
called him fri he wouldn't answer his phone, then called off a mates phone on sat he answered and said give him a call monday he will come get it....
calling all day txt even email and he won't reply
so anyone know the best way of persueing this???
trading standards? police?
as he owes me £275
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