My first instinct is to ask how come your UEs are the same when three people have a lock-up garage and the fourth doesn’t. Sounds like whoever created the original plan bothced it,
That aside, there is no way you should be paying for the new garage doors, the question is how to get around it.
One way would be for your Owners Corp to pass a by-law saying that all owners with garage doors are individually responsible for their repair and maintenance (with conditions attached, such as appearance, etc). This would pas at a general meeting even if the fourth owner objects as special resolution require that no more than 25 percent of votes (unit entitlements) vote against it. Creating a by-law would, however, cost a little money.
Another option would be for the owners collectively to make an application to the Tribunal (NCAT) under Section 145 of the Act for a variation of the payments of levies (in this case, a special levy).
If you meet with any resistance to either of these plans, you could launch an action under section 145 yourself or, if you wanted to get really heavy, say you are going for a Section 183 reassessment of Unit Entitlements. However, that might be more trouble and cost than it’s worth.
Having said that, if the value of your apartment is wildly different from all or any of the others, it’s something you should consider. And if so, your next call should probably be to an experienced strata lawyer.