Muddyfox 26\ Bike factory fault"

I bought two Muddyfox 26\ 21speed bicycles on Monday.<br> Both boxes were sealed with just three pieces of sellotape, which seemed a bit *****, as if it had been returned before and quickly half-heartedly resealed.<br> I have just gotten a chance to assemble the bikes this morning and both bikes have very faulty gears.<br> Neither of them will stay in gear for a second, they just keep jumping to other gears, and eventually the chain falls off.<br> Upon research I have noticed that a lot of people have had the same issue and professionals in the biking industry have told me,\" there's a gear shifter compatability problem, so the shifter does not match up with the gear system\". That may have something to do with the loud clunking noise.<br> I will be returning both of these bikes for a full refund, but just want to warn anyone thinking of buying a Muddyfox, Don't do it! <br> They're not the cheapest, but they are terribly made."