IMEI number blacklisted by another company as "revenge"?
This may be a bit of an oddball question, but hoping someone that knows of these matters can answer.
I have a subsidized/locked iPhone 5s via AT&T in the USA, and I'm on a 2-year contract with them. I recently (and still am) visited another country, and wanted to use my iPhone5s with a local (out of USA) phone number and SIM card. I came across a site (officialiphoneunlock.co.uk) that promised to unlock my phone. I believe my intentions were good... I just wanted to temporarily use a local number for my family to call me on while I was out of country. I still intend (and still am) to stay subscribed/paying for my 2-year contract. I feel that it is thus within my "rights" to use the iPhone with another SIM card if I want, but I suppose that's another debate.
The website (officialiphoneunlock.co.uk) clearly advertised a price of 20 British pounds for an unlock for those of us on AT&T in the USA. As I proceeded, they did mention you'd have to do a "pre-order" and that any extra costs later (if any) would have the pre-order amount subtracted from them. But.. the advertised price for AT&T USA was the same as the pre-order deposit (others such as T-Mobile were more), so I went ahead and did it... It did seem kind of fishy. It also involved me giving them my IMEI number, which I did.
A few days later they sent me an email saying it'll be an additional 150 British pounds to complete the unlock. I engaged their support, saying the advertised price was 20 pounds... they never really directly responded to that... We went back and forth to no avail... finally I told them I was going to have my credit-card company do a "chargeback". Which I did, about one week ago. Today, the unlock-company wrote me an email about that, saying they will:
1) File a claim in county court for the cost of the service, plus additional court fees (which in GBP are expensive).
2) Blacklist my IMEI number within 48 hours - They say they will make it so my IMEI will never work again on any worldwide network, including the one I'm on now.
Obviously, I should've never gotten into bed with these people.
So even though I believe 100% I'm justified in doing the charge-back... I can understand them filing a claim in court... that is their right, and I suppose I can "fight" that.
But saying they will blacklist my IMEI number... That definitely seems like they're bullying me... So my question is... Can they actually do that? Is there anything I can do now to prevent that? If they do it, will I be able to have AT&T undo it? And will AT&T help me knowing that my intention was to unlock the phone? And any other advice in dealing with this would be appreciated.