What mixer shower do I need?

breaking_free

Thanks Rodders53 but that suggestion is a non-starter: bits can't be transferred over.
 It's a solepearl brand square thermostatic mixer bought from Amazon so I can return it for free on Monday. The specs listed it as having a temp range up to 50. https://www.amazon.co.uk/gp/product/B07RXPKH7T?ref_=pe_2105081_77703951_E_Asin_Title

ThisIsWeird

I suspect your existing shower will have a similar spec, so good chance there is nothing to be gained - unless your current mixer is faulty, in which case a replacement cartridge could be the simplest way to go.

Eg: These also say up to 50oC https://www.amazon.co.uk/Thermostatic-Shower-Cartridge-Replacement-Repair/dp/B09P3RX9NL/ref=sr_1_8?keywords=thermostatic+shower+valve+cartridge&qid=1676796809&sr=8-8 and https://www.amazon.co.uk/DAZZLEEX-Thermostatic-Shower-Cartridge-Replacement/dp/B0B5QTJ9YD/ref=d_pd_day0_sccl_2_3/257-1803026-1702268?pd_rd_w=bTR59&content-id=amzn1.sym.8ec13b8a-30d2-48fc-8503-84c56766370d&pf_rd_p=8ec13b8a-30d2-48fc-8503-84c56766370d&pf_rd_r=GYZ4S7HQZKCW3BFDV0VF&pd_rd_wg=ZAab6&pd_rd_r=85ce2155-7b10-40c9-93dc-3d8098f39844&pd_rd_i=B0B5QTJ9YD&psc=1 , whereas others just don't state temps at all.

Remind me - did you remove the therm' on your old mixer? Would any of these fit? What make is your existing mixer?

Edit: You don't know the make, and you've yet to fully remove the existing cartridge. You know what I'm going to suggest

If you can find a matching cartridge that's stated as being up to '50', then that's your first move, I reckon.

breaking_free

Thanks ThisIsWeird. I will try this first as it's a simpler and cheaper option than swapping the whole bar or the entire unit!