Our heating broke during a cold spell there recently. It worked upstairs but not downstairs. We poked ineffectually at the boiler and the radiators but, in the end, we had to get someone in. He had a look and pointed out that we had a thermostat on the wall downstairs which was currently set to zero and that might be the root of our problem.
Oh joy, it happens to other people too! Look on the bright side, your heating works, as does the downstairs thermostat; and you also now know where the downstairs thermostat is.
Sounds like my relationship with IT and laptops, now I have to sort things out for myself and no longer have an office minion to look pityingly at me while he pushes the on/off switch.
It is a bit distressing, particularly if you think of yourself as reasonably competent in other fields…