The CEO should iirc be an employee of the Court, so I would be making a serious complaint to the Court he works for, especially since you have it all filmed for evidence.
Contact your credit card company ASAP and have the payment cancelled/charged back - you are NOT responsible for your exes debt, and they have clearly defrauded you, threatening to break into YOUR house for someone elses debt.
CEO's can in theory break in, but iirc, they require a magistrates warrant to do so - the original warrant they are issued does not allow this, but experts will advise on this.
They cannot take your goods, for someone elses debt. I would argue, that whilst they may legally speaking be protected had they forced entry, or stormed in as that address is what was on the warrant, you also would be entitled to defend your property since you are not the debtor, and they do not live there.
Can I ask, are you within the Dyfed Powys Police Force area? If so, you need to hold of the court to inform them they have the wrong address, and get this sorted ASAP, record the phone calls, this is to protect you and your property. Dyfed Powys appear to be very "Bailiff friendly" and have been known to turn a blind eye to Bailiff's headbutting alleged debtors in order to make "peaceful entry" into homes, so you do not want them coming back, with police backup. It's a more "out there" scenario but not completely unlikely, they have your down as a "mark" now, to use the common con man's term, and I would not be surprised if they try and squeeze more out of you.
*Asking re Dyfed Powys as Excel appear to be the preffered contractor for much of the region. It is very strange though, that both a CEO and a private Bailiff turned up, unless the second was the CEO's assistant.
If you want to protect your property and car, in case they do turn up again, or if your Ex has any other debts she has "forgotten" to tell you then you could do a Statutory Decleration will will cost £5-£10 at local solicitors, or possibly for free at local court.
I think you need to have a chat with your ex, to find out exactly what her debt situation is, ie can you expect bailiff's or debt collectors for other debts to be turning up at your home - if necessary guilt her into being truthfull, as this also affects the kids, who live with you.