Strange. Many cars have parcel shelves moulded from soft fibres, a bit like papier mache . If you have had a bad experience with a Used genuine honda one cracking, maybe an aftermarket one will ,perversely, be better.
I'd persevere with repairs . I'd only buy an aftermarket one if its custom made for your model of Jazz, and not just some generic 'one size fits all' type. If it doesnt fit then its not as described and you may be able to get your money back. -Easier if its despatched from the UK, not delivered direct from China. If all else fails you may be able to swop clips and things from the original to the aftermarket one.