My car went for a remap yesterday, the mapper ran into some problems. He said that every time he increased the boost pressure (he was aiming for 17psi) around 13psi the actuator valve would open and release the pressure. As a result of that hew has had to order me a replacement from Forge. i just want to check if this is a common fault or if not, how likely it would be, it back in on Friday so ill be checking the Worn part myself but it'd be ideal if someone could shine a light on this for me if possible.

That part is not faulty, it's just doing what it was designed to do; You are asking to much of the actuator.
Many people change to the Forge part because it can handle more boost.