Why does Amazon reduce their price daily when I’m not even competing on price?

This has got me so frustrated. There’s no point competing with Amazon on price. I’m sure we all understand this by now.

I am selling a branded product, it’s just me and Amazon. Their price was £20, so I listed for £19.99 (FBA). Daily before they even received my shipment, they have been reducing their price. If they listed it just below mine, I could understand. But they have been reducing their price DAILY and they are now at £16.90. I’m expecting to wake up tomorrow to another reduction.

Why does this happen? I haven’t budged from £19.99 and so far I’ve had no sales. I fear I’m going to have to now reduce below Amazon, and they are just going to reduce it even further! It’s barely worth selling at £20, and they’re selling it at almost £15 now. Why does this happen!?