Citroen C5 -01 - Can't open my backdoors - kwamex

So, I'm from Sweden and I'm not used to talking about my car in English, so sorry in advance, but I'll try explain my problem as good as possible.

However, first I couldn't open my backdoors and left front door (just the right one), I could get the left front door open by putting key in and turning and meanwhile it's turned I could open it and the second problem was my tailgate opening for pretty much EVERYTHING. And when I close it - it just locks itself. (same as front door - got it open by turning key, but when closing = closed)

Can't open from inside nor outside.
However, I went to SM Bilar in Sweden, they're specialized on ctiroen&peugeout.

They managed to get the left front door working properly again. So now both my front doors are working. And they think that ALL of my lockcases are burned- but if all are, why are the front doors working?

However, if they would change it, it would cost 1800€ so they thought I should try doing it myself. But what do you guys think? Is it ALL the lockcases?

And how do I open my backdoors when it's "superlocked"? Is there an easy way?

Greetings.

 

Value my car