Bicycle rack not holding so fast....

We bought a bicycle rack from a local dealer and also 2 bicycles. The bicycle rack was from this company called Holdfast. We went on holiday with the bicycle rack at the back of my caravan installed as instructed with both bicycles on. On our way back along the road the one bicycle rack mounting came loose and slipped of with the bicycle intact and we lost the bicycle without knowing. We stopped for a break 200km further from our departure point and discovered the bicycle fell off with the mounting plus one other mounting that was unused. I felt this was a manufacturing mistake and subsequently contacted the dealer who advised me to contact Holdfast. They asked us to send the bicycle rack back for inspection and all they did was repair it. My claim was that they should replace my bicycle as it was their faulty product that caused my lost. We bought the bicycle for about R6000. It was still brand new. This is very poor service.