I bought a Miband 2 from the (ill fated) Gamiss deal. Within a couple of months I strap had become very loose around the 'face' (the two layers of the strap had separated from each other). I hadn't worn in in water or been rough with it. I stopped wearing it pronto as it looked like the 'face' would easily jump out and be lost, and ordered a few new no name straps from gearbest. I had also given a Miband to my friend as a birthday gift and sadly hers did escape from its strap, never to be seen again.
Is this a known design fault with the mibands, or did we get a bad batch (or fakes?)? Electronics in mine still seem fine, and so far so good on the first gearbest strap. After all the problems others had with Gamiss I didn't bother to contact them.
Any fail safe strap recommendations appreciated.
Same problem as you, I bought a generic one off eBay and so far its held up longer. I think the more you take it out of the strap the more loose it becomes. Before I would recharge the device every 3 weeks so had to take it out of the strap. Nowadays I recharge the Mi Band 2 every 25 days which cuts down the wear and tear of the straps.
The strap is obviously the weakest part so always handy to buy a few. The one I bought was roughly a dollar off ebay, but shipping took a while.