@JonnyG thanks to @ravenstar68 posting the link to Wix Support, I was able to find something buried there that you may be interested in:
It is possible to not have to use Wix’s DNS servers, however it may not be quite so simple as I believe you mentioned that the domain was purchased from Wix?
And here we go … instructions on how to transfer a domain away from Wix to another domain registrar.
Now, I have to be completely honest here. It is always recommended to NEVER have domain registration and hosting from the same company … I think perhaps you can see some of the reason why based upon what we have been dealing with here. I presonally recommend that you transfer your domain to a different registrar. The decision is, of course, yours. 
(But if you transfer your domain to a different registrar, you will be able to have MiaB control all of your DNS as you originally wanted. Hosting with WIX simply will not allow you to do what you want.)