Magtenlight bike light self-charges as you pedal

Hello. I bought one of these, but unfortunately, I can't really recommend it.
Price: not cheap, but cheaper than a hub dynamo.
Delivery: good - about 10 business days
Product: bulky, ugly, kind of flimsy, exposed wire connections. I'm not convinced by durability, unless you're cycling carefully on perfectly flat roads.
Installation: a bit tricky, but easy enough
Looks: definitely very "my mum insists". It is not sleek, but we can forgive that for the sake of the environment.
Performance: Don't know, it didn't work. However, it makes quite a rattle, causes a little drag. From other blogs/forums, the rattle is confirmed, even when working correctly, increasing with speed.
Service: Once correct assembly was confirmed, grudgingly sent a part replacement, did not replace whole unit.
Replacement parts: Also did not work - but same rattle and drag. No further service/advice/explainations given.
Refund Policy: When the correct assembly is confirmed (I had to make videos) and product is therefore accepted as defective, you have to post it back to china with registered post, which is nearly the same cost as the unit. If they say they can get it to work at the factory, no fefund.
Refund is only for the unit, postage is not reimbursed. The company seems to be asking us to trust them rather a lot.

Comment: Even if I had got it to work, I'm not convinced by it's durability. The product needs something to weigh-up against the negatives of weight, drag, looks, inconvenience (can't turn it off), security (it's easily stolen) and cost (it's not that cheap). So far, I didn't see any. However, the company refund policy (if it works: you pay, if it doesn't work: you pay) tipps the scales for me. If it sounds too good to be true, it usually is. Customer beware.