I booked a battery replacement for my Mercedes C-class. The fitter came within the time slot but in a National Tyre van, unmarked on one side. I did not get a Halfords own-brand start & stop 80aH battery, as he told me they were having supply difficulties, but an 82aH Exide one. I wasn't bothered by that, as I know my battery brands. He struggled to put back the lower battery holding clamp, which was hard to access - that was the fault of Mercedes's bad design. Then the car would not start, showing error codes which were clearly wrong. He said he had no diagnostic equipment, told me to call Halfords - and drove off. I called and a very friendly lady organised a follow-up warranty visit 2 days later. She seemed to expect this kind of call and waived the charge for this second visit. The technician (who came in an unmarked van) plugged in his diagnostics equipment, cleared up error codes, and the he car started again. But he could not solve an error code about the active bonnet system (pedestrian protection in case of a collision). After he had gone, I found a video on YouTube of an Indian technician fixing that problem - caused by a broken cable connexion. So I went and looked, and found that the original fitter had accidentally disconnected a connector in his struggle with the retaining bracket. I reconnected that and all was well. Otherwise I would, at the 2nd technician's suggestion, have had to take the car to a garage (my independent Mercedes specialist), and send the bill to Halfords, if the garage determined that the problem had been caused by them. All inconvenient. I chose Halfords because of the convenience of fitting at my home, and the price, which was indeed competitive. Their technicians were cheerful and friendly but they seemed to lack the training and (in the case of the first one) the equipment do this kind of job - which is hardly a complicated one. A pity, as I am a strong supporter of the independent automotive aftermarket and this is just the sort of thing a well-resourced service chain should be able to do. It was fortunate that I know my way around cars at least a little bit.