Facebook review: There is an outstanding amount on my account that should not be there

I've noticed there's an unresolved balance of $816 on my account for advertisements that were run after the sale of my previous business. As I've been unable to reach a representative to discuss this matter, I'm finding it increasingly difficult to resolve this issue. Could you please review my account and remove the outstanding charge? I have a new venture that I'd like to promote, but I'm hesitant to proceed with this lingering balance from 2016, the year I sold the previous business.

And here's a version that omits the specific amount of $816:

I have a lingering balance on my account for advertising expenses that were incurred after I had already sold my previous business. Despite numerous attempts, I haven't been able to get in touch with anyone to resolve this issue. Could you please review the circumstances and clear my account? I'm planning on advertising for a new business venture and would like to proceed without any outstanding issues from my previous one, which was sold in 2016.