I also bought the same model from Amazon. In this case, the switch unit is embedded with a 3-pin socket to receive a 3-pin connector. See picture of yellow colred unit.
However, Amazon did not supply the accompanying fan-regulator so have asked for a replacement.
The question is, which one is the latest 4+1 with fan regulator, and were does the 3 pin wire lead for fan regulator fit on the Tinxy supplied unit (red coloured unit)?