To add to the good advice from @tressygirl , when your account falls below standard, Ebay email you every month to inform you of this.
The only way to improve your rating is to sell more items and get excellent feedback and to wait ... your negatives will not count towards your total after a year. You are allowed to open a second Ebay account but I think that opening a new account because you are below standard on this one is not a good idea.
You do need to change your account to a business account - private accounts are for selling your own unwanted items, not food and supplements.
Also, read Ebay's food policy and make sure you are complying with any UK laws regarding selling food and supplements.
https://www.ebay.co.uk/help/policies/prohibited-restricted-items/food-policy?id=4295&st=3&pos=1&quer...
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)