Vanish O2 stain remover. Rub it into the stain, soak for an hour, warm wash. Worked for me.
https://www.tops.co.th/en/vanish-power-o2-intelligence-crystal-white-powder-stain-remover-450g-8850360104212
Also in Big C and Lotus.
I don't know what they are called here, but this 45A double pole switch is available online...
https://www.ubuy.co.th/en/product/1N4TR4N06-45-amp-double-pole-white-plastic-cooker-switch-shower-boiler-2-gang-isolator?utm_source=website&utm_medium=product_page&utm_campaign=country_navigation_popup