Many years ago I bought a custom 'bike from a small but well-known maker. After a couple of weeks and on the first time I'd used it "seriously" (i.e. to go two miles down the local shps and back, rather than round and round in the close whilst setting up saddle, brakes etc), the steering stem broke at the bottom of the thread. LBS reckoned it was too deeply threaded, I had no confidence in a frame maker who would do that and wanted a refund, which was refused.
To cut a long story short, I took it to small claims court, saying it was unfit for purpose: Court decided that as I had ridden the bike and kept it for two weeks, I had effectively accepted delivery and was not entitled to a refund

. I could accept a repair if I was so minded but (!) they found it perfectly reasonable (given the nature of the failure) that I had no confidence in any repair by the maker

. Court asked the maker whether he didn't feel obliged to compensate me for what was in fact a 'non-bike'; he didn't, again offered a repair

. Court said that the ownership of the bike was mine, repeated that I was not entitled to a refund

but ordered the maker to pay compensation (because I had paid for a bike and effectively didn't have one now)

. Said compensation just happened to marginally exceed the cost of the 'bike (covering my costs too)

.
Finding your way to satisfaction through the law can be complicated, but occasionally rewarding.