Trunk Lock spring

Ok so I have replaced the trunk Lock assembly in the past and discovered it was from the spring in the mechanism being too weak and stretching.

Not longer then a few months later with the brand new mechanism, the spring again stretched and left me crawling through the back seat cross bars.

Is there a better replacement part I can get for this so it doesn't keep occurring? Would it be wise to make my own spring out of a heavier gauge wire? Im not really keen on this taking my back seat out thing every couple of months. :oops: