Someone's been messing with the wiring and put it back together wrong. an electrician should be able to sort it out in under an hour.

It seems your switch lines have been mixed up. As long as the right cable type was used for the original installation it should be a straight forward job

Thanks

If you insist on doing it yourself ENSURE POWER IS OFF
Look for the 3 core and earth cable (either with red,yellow, blue colouring and earth -green/yellow or if a newer install, brown black grey and earth)
on the back of the switch there are 3 'holes' labled COM, L1, L2. make sure the same colour is in the same hole in both light switches i.e. upstairs and downstairs. If there are more than two switches then its much more complicated as then you have intermediate wiring. be aware there will also be other cables in the back of the switch as well as the three cores ones. The norm in old colours would be the yellow (from the 3core on its own in COM, red in L1 and black in L2) L1 and L2 are normally the ones with other cables in, at least at the "master" end. likely is reds together in L1 then black and blue in L2.
ENSURE POWER IS OFF, this advice is based on a number of assumtions and cannot be guarenteed accurate.

If it’s a Two way Switch (As in 1 switch upstairs and another switch downstairs both controlling the same lights as an example) ‘Normally’ with that problem you’ll find that the wiring for the 3core and Earth are not co ordinating. So put two and two together and bobs your uncle or it could be your aunt, but it’s highly recommended to let a professional carry out these kind of work... for your own peace of mind.

Switches are wired wrong, easy job for an electrician to rectify. Post a job on here to get a few quotes.

可能是一个简单的方法,因为它可能是西南itches have not been connected in the correct way, in that the upstairs and downstairs two way wiring has been mixed up. The worst case is that its been wired wrongly and was never meant to work as a two way set up and so just needs returning to independent up and down operation. Its not really a DIY job that you can solve yourself, so best place a job here on mybuilder and get a couple of quotes.

Hi there , the light switches are connected up wrong have you replaced these switches with a decorative type ? Anyhow this is complicated to figure out the connections if you don't know how it's meant to function and would be happy to help if you need me to

Adam

hi lewis
post the job it should be easy enough to sort out your wiring is mixed up, shouldnt take long to sort out . regards jeh

Configuration of wiring within switch is incorrect. On site inspection would be necessary to repair and enable lighting to work properly. Telephone advice would not be recommended due to inexperience of customer with electrics. Safety is the main issue.

Posts job here
Any decent spark would sort it out
It sound like
There were no two way switches in first place and someone tried to make this possible .