I had almost exactly this issue with Skype earlier this year - they locked my account from using credit, meaning that although I can still log in and make free Skype-to-Skype calls, I still have $10 of Skype credit that it prevents me from using (as I got locked out soon after an auto topup). From what I could tell, my account was compromised for a week, and there were several spurious messages being sent from it, until I finally realised and changed the account password. I emailed customer support several times to unlock it, and provided a whole host of legacy data about the account (which had been set up back in 2005) and how it had been used over that time, but none of it helped them to confirm my identity. Out of frustration, I wrote to them to get them to point out exactly where it said that they could take this type action. They couldn't give me a clear answer, and like the above poster, they suggested I just create a new account. Here's the (almost kafkaesque) replies I received from them:

> Hello,
>
> I understand that your concern. Please see all the
> answers to the following questions.
>
> 1. To have this issue escalated to a senior manager.
>
> Please be informed that this case has already been
> investigated by the higher department and the result
> is that the account should be remain restricted.
>
> 2. To have it pointed out where in the Terms and
> Conditions it says that you're unable to tell me
> the underlying reason for the restriction.
>
> I am sorry but we cannot disclose the specific reason
> why the account is suspended. You may just refer to
> Terms of Use number 11.
>
> 3. To have it pointed out where in the Terms and
> Conditions it says that you're unable to refund me
> the money on my account. OR to have the $10 credit
> on the account refunded to my Paypal account.
>
> Kindly review Terms of Use number 10.6.
>
> 4. To have all my payment methods removed from the
> account, to avoid the potential for abuse.
>
> I would like to apologize but we no longer have the
> option to make changes on the account since it has
> already been suspended due to this kind of concern.
>
>5. To have the account completely shut down, not just
> restricted. (OR to have it pointed out in where in
> the Terms and Conditions it says you're unable to do this.)
>
> It is already our internal rule that we cannot make
> any changes on the account like cancelling the
> account once it has been suspended or restricted.
>
> I hope that I was able to answer all your inquiry and
> I would like to apologize if we can no longer assist
> you further regarding your concern.
>
> Best regards,
>
> Diana B.
> Skype Customer Service

====

> Hello,
>
> I am sorry to know that your account has been restricted.
> I understand how important it is to recover your account.
> However, your account has been detected that there are
> some activities which are contrary to Skype's Terms and
> Conditions have taken place via your Skype account.
>
> Following our investigation, we are unable to reinstate
> your account. Please understand that we are unable to
> explain the specific reason for restricting your account
> and this account needs to be remain restricted.
>
> However, you are always welcome to create new account
> to continuously enjoy the free services and features
> from Skype.
>
> Best regards,
>
> Diana B.
> Skype Customer Service

To add insult to injury, I notified Paypal (which I used for the auto topup payments) to reverse the charge, owing to misconduct by Microsoft in refusing to unlock the account. After a week in which they did "their own investigation", where they didn't even contact me for any corroborary info, they refused to issue a refund. All I got was this 2-line reply:

> We have concluded our investigation into this case. Unfortunately, at this
> time we are unable to decide this claim in your favor.

Made me think that they're secretly in cahoots with Microsoft. I was pretty livid about the whole experience, and it's seriously damaged my trust in Microsoft services.