So money probably wasn't what caused them to be locked. So the probable reason is
Terms of Service related then. (The Dispute Policy is located
here, which may also be worth looking at.)
They don't really have rules against registering domains but not using them... though they do have rules against squatting on domains for the purpose of selling later. Like if you registered iphone7.com simply so when the iphone 7 was going to be released you'd sell the domain to apple for big money.
And the sites you had connected to them weren't for the purpose of catching traffic off other sites to redirect. (Like you didn't register microsoftw.com or microsoft.pw simply to get traffic directed at microsoft. )
I do find it odd that they would ignore you when you asked for more information about this incident... (Make sure you check spam/junk folders just in case they sent something but it got filtered. Which might happen if they use an address you haven't purposefully whitelisted.)
And if you didn't get anything then I think you should try filing another
support ticket. (Try filing it under "Domains - Legal and Abuse". That may give it a bit more urgency and plus they may explain why your domain was locked and the steps you can take to regain access/control, if it's possible at all.)