ParcelHero is one to avoid, in my experience. They came up on one of the compare sites when I last posted some bits I sold on here. I used the new Royal Mail collection for the first few items that I sold, but then got bogged down with work stuff meaning I had to get a next day collection (or so I thought) for the last item. The Royal Mail bits cost less than a fiver, but ParcelHero (using Hermes for the actual courier service) was just shy of £12 for a similar size and weight for the advertised next day collection. My own fault for not being organised, I thought. Anyways, it took four days for them to collect. ParcelHero customer support number was a dead line and Hermes by phone only allowed the input of a tracking number and then gave an audio message saying the parcel was due to be collected. Exchanged a few emails with ParcelHero, but just got fobbed off. Won’t be using them or Hermes again.
I’d imagine the Royal Mail service has a size and weight limit, so probably no good for a seat box. But good value for others sending reels and other small items.