didn't honour warranty

I bought a bike mail order from them. Was on sale at a good price. Bike arrived poorly set up. Brakes rubbed from day one and pistons (in disc brakes) would.t fully retract. This ended up causing piston seals to fail. I spoke with Winstanleys they told me to return brakes and they would see if could be repaired under warranty and said postage would be refunded. I did this and they advised that the fault was as described above caused by too much brake fluid. It was them that set it up wrongly like this, but they are now charging full price for parts and labour for repair, not honouring warranty and making me pay for repair. This would not happen with a shop you could just go into. They don't return my phone calls and only apply to some emails. I think they have been terrible and should refuse to pay, but they have had my brakes for weeks and I've not been able to use my bike so I have just paid them. If using winstanleys expect poor after care and no warranty.