Yes go for a new bike.
Tredz seem to be on board with you - let them embarass the courier.
By the by, Hermes turned up at my door with a package the other day - it was for a neighbour and the courier chappie was very good about filling in details, informing the neighbour. I told him his company had an awful reputation and he was aware of lots of bad customer feedback for this south London patch.
Lots of courier companies are wonky these days. I have had a computer (clearly labelled as such) left on my doorstep when I was out. I think that was "Royal" Mail. I have also had royal mail ring my bell and then just trot off leaving stuff on my doorstep, not waiting to see if I was actually in or not - they could have had no way of knowing that I was actually in. I chased the chap down the estate and he was entirely unapologetic. Next time I complain.