Broken sliding rear seat 2001 zafira

HELP - the passengers side of the sliding rear seat wont work. The drivers side seems to engage and disengage its locking mechanism and slide a bit, but the passenger side wont disengage and is lonked in place, this the drivers side wont move either. Ive managed to get a screwdriver into the mechanism and free it up (once), but i cant do it again so its stuck.

Is this a common problem ?

is there a fix ?

Any help apprechiated.