I agree with what the others wrote here. Imo, it's unlikely that the jacket is actually leaking.
However, it is common for jackets to wet out soon if they are not brand new anymore. The so-called Durable Water Repellent (DWR) layer is not durable at all, so very soon the water isn't beading off the jacket nicely anymore. Also Nikwax is very overrated imo. My experience is that a treatment doesn't last longer than a few hours.
If the jacket wets out, it still won't leak, but it doesn't breathe anymore. So condensation becomes a much bigger problem. A wetted-out jacket doesn't perform better than a plastic bag. So the DWR is really the Achilles-heel of any waterproof jacket. Another cause of getting wet is water simply entering via your face and neck, and via the sleeves. Water entering via sleeves is often a problem when walking with poles.
Personally, I don't bother with expensive jackets because I don't see the added value. The most I've ever paid was £70 for a Marmot Precip. It doesn't leak, but I get wet anyway because of condensation, like with any jacket. If you look at the specifications of different materials (GoreTex, eVent, etc), it's clear that the breath-ability of any materials can never keep up with your transpiration so you'll always get wet eventually, except perhaps on very easy flat walks without backpack.
However, even if you get wet, the jacket still keeps the wind out (and most of the water), so it is still very useful. I can also recommend a merino baselayer to go with it because it can keep you warm even when wet.