Mondeo 2005 st tdci n/side light fault

[Mozza83]

Ok so here goes the other morning jumped in my car at 5am and it was very very cold outside. Turned on my heaters and they made a funny rattling noise, so knocked them off for a few mins while the car warmed. Now when I tryd to put them bak on nothing, seems there was no power.

so on my break I pop out to check the fuses and cause I don't no which ones the right one I start pulling them out 1 by 1 checking them. Found a popped fuse so put in a new one and there's my heaters working again. Now at this time I'm not thinking about any lights being out so can't be sure when they went out. Either the same time as the heaters popped the fuse when I checked the fuses.

Now I get home pull my car on the drive get out and realise there's no rear side lights or brake lights on either side, still getting my third brake light working thow. 

So I decide to check the fuses out again so look under the bonnet and there's 2 fuse popped. Change both fuses and now I've got sidelight on the drivers side but still nothing on the n/s. And still no brake light on either side. So I decide to check the fuses in the car behind the glove box and there's one fuse popped. Put in another one and its pops, 10 fuses later  lol and still popping. 

So now I changed all the bulbs over from the drivers side cluster to the n/s and still nothing but all the bulbs from the n/s work on the drivers side so can't be a bulb fault.

I disconnect the n/s rear cluster put in a new fuse and I have my front sidelight again but as soon as I reconnect the rear cluster it pops my fuse again. 

Now can anyone help as I no nothing about electrics and fords as I've only had the car a few months.

Could it be a rear cluster fault ????? 

And all lights was working fine before my heaters popped the fuse ??? 

 

[isetta]

https://www.ebay.co.uk/itm/Genuine-Ford-Mondeo-MK3-O-S-Double-Pole-Bulb-Holder-1327490/272375084828?fits=Model%3AMondeo|Cars+Year%3A2006&epid=1609774052&hash=item3f6ad1f71c:g:4m0AAOSwE0JY-bpl

does the bulb holder thing look like this?  if the fuse only blows when you plug the cable plug into the plastic bulb holder thing then the fault/ short circuit must be here. 

does it blow when you plug it in even if no bulb in the holder? 

is it possible to get the plug upside down by mistake? 

look inside the plug - are any connections bent so they touch eachother when they should not or are out of line so they connect with the wrong connections on the bulb holder thing.

are any of the pins on the bulb holder thing where the plug goes in bent so they touch eachother or connect with the wrong part of the plug. ?