If the trolley pusher doesn't blame the trolley as being defective, it may well be that that person is responsible.and if fhey have personal liability cover (included in their Home Contents cover), they may be able to pass the responsibility onto their insurance. co..
Regardless, the conditions of your motor policy demand that ALL incidents are reported. Depending on the quality of your cover, (and this is where the cheapest is not always the best), they may take action against the third party hid ins co. It's not up to you to do anything other than report at this stage - but you may lose your NCB if thet find it easier to pay for your damage rather than pursue the TP