Sony Xperia Z1 Compact Replacement Port Covers
Unfortunately, I've also fell victim to my cover ports snapping off which in turn nullified my phones waterproofing.
Seemed to be quite a common complaint about the Z series before they made the ports waterproof without the need for covers.
I was browsing whether it was worth claiming on my insurance before stumbling on a repair video to replace them and it looks painfully easy to do. The example in the video had just the frame disassembled, but the author said they could be put in place with no disassembling required.
£8 purchase from eBay. Wish me luck!