Sendle SmartSend and PackNSend have over 1000 reviews and are still 4/5 stars.

https://www.productreview.com.au/c/couriers.html

Australia Post and Couriers Pelase have about 2/5 stars based on 4000 reviews.

Startrack (part of Australia Post), Fastway and Toll have 1/5 stars reviews of which Fastwya has the most reviews.

If you are happy with Fastway, you ought t give them a good review to help pull their ratings up. also notice the products you sell are quite small and low value and would fit in a postbox easily. try sneidng somethign bigger where the courier has ot leave it in public.