So basically had the OP read the T&C’s, they would know that what they were selling was against policy, and as such should not be blaming Shopify. Sounds like a case of lets blame anyone but ourselves.
[Mod Edit to remove content that break the Forum Golden Rule – Be nice, respectful].
Even then, I dare you to find the particular policy, guess what, it’s not even on their signup page. So, please go troll another thread, I asked for help and advice, not your opinion.
Unfortunately, like an earlier poster said – this is what happens when you have a website based on another platform. Not the same as being solely reliant on eBay for sales but it has similar downsides if and when you infringe on the platforms rules.