I am sorry to hear your new wrist and thumb splint is not working for you
. I have recently been given something similar to yours by the orthotics dept at my hospital. It is a standard "skin colour" NHS one but the thumb part is separate to the wrist part. I tried to find a picture to show you but I couldn't find one I am afraid. I do find that by the end of the day the web of skin between my thumb and index finger is quite sore (almost cut) but I can loosen the thumb section off to ease the pressure. The thumb piece is fastened by velcro in a circular fashion around the thumb (if that makes sense
I have differnet splints to wear in bed to stop my hands going numb (from Carpal Tunnel) and one time I had a nap in the afternoon and forgot to change my splints over and that was quite painful between my thumb and finger, but other than that I have found them to be quite good.
I do struggle to write with them though, but typing seems a bit easier. The orthotics dept bent the metal inside to the shape of my thumb and I am able to use my crutches a lot easier with this than my old neoprene and towelling splint which I had an allergic skin reaction to. Also my OT has recently installed a stair rail for me and the metal in the hand part has been bent in such a way as it is comfortable to grab onto the rail going down stairs (the old splint was too uncomfortable to do that).
I wish I could find a picture to post a link for you. It is made by Promedics (which I think is the standard NHS supplier) so perhaps you could track down a link or see if your Orthotics dept can provide you one of these (apologies if you have already tried this and it was no good for you).