In trouble with my assurance (cheated, need help?)

Hello my dear swissies.
I am writing to you guys, because I acutally have no clue what to do and I need some adult adversing.

In the end of 2014 I subscribed to Assura for the normal assurance package, i got the contract and everything went fine.

THEN in beginning of 2015, I arranged a meeting with the Helsana-company where an emploi comes to my house to explain me the benefits of their assurance (which actually was better than the one I already have)
- so I make an agreement, that I would change to Helsana in the beginning of next year (that meaning 2016), they sent me a contract and I sign.

But now they are sending me bills, they registred me as I submitted THIS year so now I have TWO ASSURANCES which I cannot pay and they refuse to let me cancel our contract.

Is it even allowed to have two assurances? Status quo is that I have to assurances, I can't pay, I just got to the country and I almost got the feeling that they cheated me. Do you guys have any (legal) advise? Can they do that?

I already call them and they say it's fine, they would cancel this mistake but they keep sending me more bills and refuse to cancel.

Please help, I'm confused.
With love from fribourg.

In trouble with my assurance (cheated, need help?)