The Government has no time for small fries like you
Technocracy appears to be a monolithic Big Brother, spying on everyone at all times, but the truth is that their goals can leave even the best among them strained. Even the most oppressive governments are loath to devote precious resources (people, equipment, processor time) to small threats. In fact, such a government would rather apply pressure by threatening the well-being of a dissident (withhold important documents, make it hard to find a job, have a person known as an anarchist) rather than actually doing something drastic (investigations, summons, lawsuits, arrests).
The most oppressive way to threaten is to keep someone in the dark. The System has to be impenetrable and capable of anything. Your players seem to misunderstand and think that the System will play by the rules. It will not - it makes the rules instead. Laws, police force and courts are for regular criminals, who need to be stopped. Your characters however are more than that - they are dissidents, stark enemies of the System. A smart System operative would exploit their situation in three ways.
There are things you want from the government
Like a passport maybe, a place at a public kindergarten, driving license. Or maybe you'd like the police to properly assist you when you're mugged by "random" criminals? Or actual, dependable healthcare, without risks of complications? Or maybe sick pay or a pension? There is a lot of stuff that the government actually provides (at least in the EU) and your PCs will need those from time to time. Actual bureaucracy, delays, not being taken seriously. Hardly anything will demoralise a person more than reporting an assault (or other crime) and hearing "Are you sure you didn't provoke them? I mean, look at you. Who goes out that late anyway?". And then the case gets closed under "perpetrators unidentifiable" bull.
You have something to lose
As you said, there are families, posessions, freedoms. These can be taken away or better yet, threatened to be taken away. Democratic societes take a lot of stuff for granted - right to work, right to travel, right to gather. Imagine that a PC want to go to Spain for vacations, but every time he passes the border he is labeled for extra checks that make him miss the flight. PC's family can go, but not the PC. Maybe the boss will one day approach him and say that there are redundancies and sorry but he has to go. Don't do that to the players just yet! Mention that a friendly NPC has those troubles and make the NPC no longer willing to help.
There are things you want to hide
You said the characters committed some crimes. Lucky for them! They get to walk scot-free. Maybe a routine hearing that goes terribly, maybe a day in the jail, but afterwards, with no explanation they hear they're free to go. Let those accumulate, it's perfect blackmail material. When they go against the government in a serious way, a skilled operative will give send them a court summon. This can of course go away, but if and only if the characters cease all unwanted activity. And if they turn their contacts in, they might even get rewarded...
Usually, a single government operative would control about twenty cases at any given time, with many more than that being monitored. These people are often masters of coercion and can achieve compliance in a number of cost-effective ways. If the target is showing no signs of improvement, they would start building a net of contacts, helpers, snitches and spies around that person. In the end, however, it's control what they want, not termination. Especially Technocracy is much more fond of reprogramming and repurposing Mages into their ranks, either by invitation or by force than terminating them outright - that's considered inefficient.
In Mage Ascension such people would be known as Men In Black. They would indeed concern themselves mostly with Reality Deviants (Mages) and other undesirables (vampires, weres...) Now, what I wrote is what happens before they catch on that PCs are Awakened. What they do after is a topic for a different question.
The above is written partly from experience, partly from real life. IF you would like to know more about specific techniques, read up on the Secret Police in the Eastern Bloc and how they operated during the Cold War. It's a plethora of information and exactly what you need for evoking a totalitarian, oppressive state spewing propaganda, by showing it's dirty underbelly.