Ethical issue with colleague, how do I handle this?

I will preface this by pointing out that the way our organization is structured, we have a "new business" team, who signs on new customers, and the account managers who take care of and (hopefully) upsell from there on.

I had a new, larger, account drop into my book of business about 4 months ago from new business. I knew immediately that this account would require some taking care of, but when a client is brought on from new business it should be ready to run transactions and bill. Well, this client was 3 months behind on coding for our API and was contracted to bill and be charged a significant amount of money when they couldn't even use it yet. New business guy got paid on this commission nonetheless. I had to go back and re-contract them, give them 3 months free so they could develop, and have them sign a new 2 year deal that had the exact terms as the contract the signed when they came on board.

Everything has gone smoothly since then aside from a legal issue the new business rep missed, causing the customers data to not be sufficient, which I once again had fixed. Well 3.5 months later, they're ready to release and run transactions.

Yesterday, I get a meeting invitation from the CEO of the company, with the new business rep on the call as well. He's not supposed to have any sort of interaction with the client after it has transitioned to a managed account. Turns out, he's been making personal calls to this CEO for the past 3 months unbeknownst to me. The IT guys with the company have spoken only with me getting their account straightened out. Then, later in the day, my boss asks me why my client is saying I lack the business acumen to handle their account because apparently the CEO told the new biz rep who went to our VP and told him this? I have had two onboarding calls with the CEO, and have fulfilled every request and even saved them thousands of dollars in the process.

What would you do in this situation? My first thought is that my new biz rep, who already has a sketchy reputation, made the whole thing up considering I've had two 5 minute conversations with this CEO so he really doesn't have a lot to go off of to measure my "acumen". Also, this CEO has apparently offered new biz guy a job.

My other thought is that he did say this new biz rep poisoned this guys thoughts about me somehow.

The only thing I could thing of that could be portrayed as a negative would be the contract situation. But, I don't get paid on the contract I have signed, I only get paid on what they bill. So in reality I lost money the past 3 months they didn't bill and had a new deal set up for them was doing them a favor.

Would love some advice or feedback on this. Thanks