By-laws are not the same as the Strata Plan.
I suggest that you ask your Strata Manager for a copy of the By-laws. If you don’t have a Strata Manager then ask a member of your Committee for a copy. If the garage has been granted to the Lot owner as Exclusive Use then all of the conditions etc will be contained in the By-laws.
By-laws must be reasonable. They cannot be unjust.
By-laws, even Exclusive Use By-laws, can be amended either: on request of and with permission from the owner who has the Exclusive Use OR; by Order of the Tribunal if the Lot owner unreasonably refuses consent to amend the By-law.
It is far easier, cheaper, and less stressful to go down the route of obtaining the Lot owner’s permission for an amendment to an Exclusive Use By-law.
Can you come to some arrangement about access that is not going to inconvenience the Lot owner who holds the Exclusive Use?
Or is the door to the storage locker able to relocated to a different position that does not impact the Exclusive Use?