Freelander roof bars misleading adverts

[jmmcmullen]

hey everyone. so i researched the correct part number for my roof bars as there are different bars for different variants of freelander. using the manufacturers part number in the search i found a seller, selling OEM style bars not manufactured by land rover. the advert stated these bars were similiar to landrover part number LR007220 (the part number i wanted). So i bought them. they came very quickly -top service. so i started to fit them. bars are secured by three bolts on both sides of venicle roof. i started to bolt down centre bolt and without much turning force the bolt sheared. i cursed my luck and concidered using just front and rear bolts to secure bar. the rear bolt sheared as well!! i'm an engineer so i understand torque and there wasnt very much applied torque at all. i contacted the seller to say two of their bolts had sheared, only to be told that the product they had sold me and said was similiar to LR007220 was in fact incompatable with my vehicle. i asked for a returns number to send back the incompatable product but they have informed me that because i had started to fit this and the bolts have snapped, that i cant return the item for refund? 

i get that there are two bolts which are now approx 5mm shorter than original but surely i must have some recourse? can i tell Ebay "item not as described" strictly speaking they sent what they advertised. very misleading wording to make people(me) believe the product was the same as the one i need!!!

Please help- as at the moment i have a very expensive roof bar set that is no use what so ever!