However it turns out that the remote controls are not at all easy to use, the instructions are hopeless and the are pretty unreliable as they lose the plot regularly, fail to regulate temperature and go into sleep mode within a couple of minute, so I wondered if it was possible to bypass the remote control feature and use a socket adapter type controller such as these https://www.amazon.co.uk/KETOTEK-Thermo ... cx_mr_hp_d
I opened up the unit on the heater to take photos in the hope that someone can figure out if the modification can be done, whilst retaining the on/off switch and the thermal cutout it is said to have.
I think you are going the wrong way. You say that you have bought two heaters which are barely useable, and if they were bought through Amazon send them back and get your cash returned. (Which? will help you if you have problems about getting the first sellers to pay up.) Buy something which will be what you really want! Remember that very cheap stuff is usually thrown together.
My opinion is that trying to remake your two heaters into two entirely different devices is doomed to failure. Don't alter electronics which is powered by the mains if you are not competent in dealing with mains wiring and know what you are doing. Electricity is very dangerous!
Hope this helps.