Passing the buck

So in 2015 I purchased a bmx mongoose bike from the store paid 7000. The chain broke went their a view days ago ask for a chain purchased it then it broke after riding a view meters. Took it back guess what they just say we dont know why chain is breaking we dont repair bmw bikes anymore dont know????? But you were happy to take my money along with we do fix bikes bring back if you need something to be done. Disgusting service they just pass the buck sorry we no longer sell bmx we dont repair bmw anymore. I will warn people not to ever purchase from you. Word of mouth a powerfull thing.