Up until a week ago I would have marked decathlon with five stars. However though the products are first in class for value and quality the service in my local store is not up to scratch. Items that are advertised as being in stock are often not on the shelves. When I enquire if there are any elsewhere in the store staff are very quick to say no, they don't even attempt to look. I took my bike to be serviced, staff member seemed to take his time and perform a thorough check. I was impressed until the next day when I took the bike out and the chain kept slipping on small rear cog. I took it straight back to the store and was advised that the change was worn. Besides the fact that it had worn after only 600 miles, this should have been picked up in the service. Also as it had been slipping since the service it has damaged a cog on the cassette. I was advised by staff member that they would fit a new chain free of charge but I have not called in since. I have since purchased higher end KMC chain, rather than BTWIN, and SRAM cassette and will be taking it to the store to fit. I hope they will honor the free fitting. Though I have had negative experiences I still will use the online service. My local store is Belfast and the most recent staff member in bike shop was Andy.