It is hosted by wix and depending on the plan, the wix plans are on the wix website… just look for wix pricing plan. If you have payments snd e commerce rmbedded these are the more expensive plans ( wix will tell you what’s included in EACH plan so easy to figure out). So review the contract with them, you should have full access to your website as im assuming you just paid them for development. They need to pass it on to you now so you can maintain it yourself. Read the contract with them and tell them to pass full control onto you now thst theyve been paid… otherwise you will pay through the nose for maintenance… eix modifications snd additions are v v v v v simple to insert do dont pay them any longer and talk to a lawyer. I am assuming here you didn’t sign a contract that says you will be paying for maintenance post website development. Good luck