Tamarillo Being eaten alive

So I got a Tamarillo as a gift and it is being eaten alive by aphids, white flies and many others.... I have tries every spray the local nursery has advised and no luck. It is also causing it to grow taller as the lower leaves keep falling and its growing up. So I plant to move it inside to quarenteen it in hopes of trying again with some native pest repellent friends like rosemary and marygold. I also want to dwaft it so I can pop a bug net over it to try and give it even more protection.

Its trunk has not fully gone woody... could I just self graft it to its own trunk?

Or should I try and just cut it down... and hope it sprouts leaves lower on the trunk?

Any advice would be helpful, I am in Qld and it is in a 60L pot.