A friend of mine took her cycle in for her 6 months service, she collected it on the way home changed gear and the chain came off the sprocket and wedge between the frame and wheel, she luckily wasn't hurt.
I went to recover her cycle and it had to be walked back a distance of 6 miles I had a look at it, not only was the back wheel lose on one side but the front brake blocks were lose too, as she had no car to return it to
Halfords, I was asked to make it road worthy which I did, I rang Halfords to say why I had fixed it to be told because I had fixed it they wouldn't touch it or admit they was at fault!
The last cycle I bought from them was a joke and all the day was to keep fobbing me off with lies until in the end I lost in with them and oddly enough a new sealed bottom bracket was fitted!
I'd warn EVERYONE not to go within a mile of Halfords if I was to say they are rubbish that wouldn't be strong enough, please beware of Halfords fellow cyclists, I'd not tust them at all.