I totally agree with the op and can see why he has posted this (to warn others) and I also agree with him still getting a replacement because the bikes a bargain.
But lets have a bit balance, not all Halfords employ crap mechanics, I usually build my own bikes and sometimes wheels and after 50+ years of doing so like to think I am capable., on a ride on new years day I had a crank come loose, I took it into Halfords, the lad replaced the bolt with a new one and torqued it correctly all for nowt, I have bought stuff off him before and I would have no worries if he a built a bike for me, I would still check it over though as I would a bike bought from a LBS.
Its a bit like saying all cyclists are idiots because you have seen one going through a red light.
But lets have a bit balance, not all Halfords employ crap mechanics, I usually build my own bikes and sometimes wheels and after 50+ years of doing so like to think I am capable., on a ride on new years day I had a crank come loose, I took it into Halfords, the lad replaced the bolt with a new one and torqued it correctly all for nowt, I have bought stuff off him before and I would have no worries if he a built a bike for me, I would still check it over though as I would a bike bought from a LBS.
Its a bit like saying all cyclists are idiots because you have seen one going through a red light.