The 2 wire actuators require an electronic drive that delivers different polarity for lock and unlock.
Your car has two coils wound on one bobbin, one for lock a situation, one for unlock.
You cannot use a US actuator, it is not interchangeable.
You need the 4 wire/dual coil part. Your msg is confusingly written, but it sounds like the4 wire part works, but weakly? I'd look for other problem sources in the mechanism, or perhaps the drive electronics. This sounds beyond your ability, so take it to someone who understands electronics.