Buyer leaves ~70% negative feedback on orders, what can I do?

[refresheners]

This guy has a penchant for leaving negative feedback and he's gone and done the same with me despite (in my view) I've fulfilled my order correctly.

I've asked eBay to remove the feedback what are my chances and if they decline will I be able to appeal?

I'm a new seller and had 100% + feedback until this person left this 1 negative feedback which pretty much annihilated any trust I built up.

In the long term what should I do? Should I start a new account?

I'm also afraid he will request a chargeback via PayPal (according to another seller he's tried that on), how can I avoid this? I've asked him to send the items back for a refund but he just replied with "Sure"

EDIT: I don't know how to leave a reply to this post but I wanted to say thank you and give an update: I just got off the phone to eBay and they removed the negative feedback! 

The lady checked that my photos and description matched up and verified everything looked legit and then removed the negative feedback 🙂

Also asked and I confirmed that I left "report a buyer" message so that the buyer account *may* get looked into.

Thank you 😄