Evans Cycles

They spoke to the shop and when I went back this afternoon the assistant manager gave me the £13 back in exchange for the tool.

So, a happy ending.
I think evans no longer record purchases under £30 on their system. I had this problem trying to replace a cateye rear light that had for no reason stopped working. Ended up using a bank statement to prove purchase and got it exchanged, about 10 months after purchase. Then when the replacement stopped working as well, I got that one exchanged too with no hassle. Holborn seem to be pretty good these days.

BTW, I bought the ritchey torque key with replaceable bolts online (from sigma sport, I think).