Am sorry to read this, not good for the blood pressure.
(DON'T get me started on what should be done to such thieves. For once Sharia law does look appealing)
Too late to be much help in this case, but may help others to avoid such event.
If your garage door is of the Up and Over type, the diagonal reinforcements only have pop rivets on one side.
Apparently, it is a popular ploy to flex the door, so as to spring past the latch at the top. Placing another 3/16 (4.5mm) pop rivet on the other side of the top hat section reinforcement will strengthen the door, and make unauthrised entry less easy.
If you access the garage via another door, so that the main door is only opened as and when required, drill a hole through the moving latch, above the catch plate, and insert a pin, or even a bolt and nut. It does not need to be big, 3/16" / 2 BA / M4 will quite sufficient, (They won't shear that easily). This will prevent the latch being disengaged from the catchplate.
The central lock, is often carried on a plate which is pop rivetted into the door. If the four rivets are drilled out, a hand can be inserted to pull down the wire that is connected to the catch, REplace at least two of thos rivets with dome headed bolts with nuts on the inside. If possible use self locking nuts or anaerobic sealant to prevent the nuts loosening.
No dome headed bolts? Turn off the hexagon, and radius the head.
If you make it difficult, the unmentionables, will find somewhere easier to burgle.
A security light may help, as long as it doesn't provide light for them to do their worst.
If the garage has a side door, it would be worth making sure that the lock is 5 lever, to be difficult to pick.
(For my shop I specified a five lever, but in the event, the door came with a six lever lock, which is even harder to pick)
Hope that some of this may be of some help.
Howard