Welcome to Bladeforums.
Where in the world are you located . Not your address, just country.
You could try to contact the manufacturer. It sounds like the knife could be defective, and they should either fix it, or replace it.
You could also try to contact the vendor who sold it to you. Depending on how long you've had it, it might still be under their warranty (if they have a warranty), and maybe they can provide a replacement or a refund.
If the lock failure is the result of defect, a repair could be very difficult if not impossible (cost prohibitive), especially if the failure is the result of premature wear of parts.
Which model is it? The most expensive Salamandra locking folder I see costs about 70 euros, which is currently around $67. But perhaps there are some I'm not aware of.