MargieD,
Does the electrical switch room contain the circuit breakers for yours (and other) units or do you have a switchboard in your unit?
If it contains your circuit breakers, and a lock has been put on which you don't have the key for, may not comply with the Australian Standards which state you must have 'ready access' to your electrical isolators/circuit breakers at all times.
If the switchroom just containes the meters and main 'building' isolation switches, then the Owners Corporation has done the right thing.