Dell Wireless 5530 Connection fails with error 734

​I own a three month old "Latitude XT2" and aside from a few minor quirks the only complaint I have with it is, that for the life of me, I can't get the WWAN card to work.​

​since I got the laptop, whenerver I open the "dell connection manager" to enable my integrated broadband card, it would just say "initializing..." for a few minutes, then the card would disappear entirely from my system, only to be recognized and displayed as "initializing..." again and so forth.​

​I have already had my mainboard replaced by dell (unrelated issue), as well as the broadband minicard itself.​

​I also reinstalled twice (I'm running windows 7 32) and on my last try, I used the integrated modem features in win7 to connect through the card.​

​It seems to connect alright, but after checking username and password, the connection fails with the error 734 (something about the PPP control protocol being terminated).​

​The SIM can't be at fault, since it runs perfectly fine in the usb-adapter that came with it. ​

​It's an O2 SIM and I got on the phone with them to make shure I had the correct modem settings, so I doubt the problem lies there.​

​The dell hotline kept sending me off from hardware to software-support and back again and the last time I called, they suggested to me, that this propably was a software problem, and consequently I had to pay between 59 and 89 € for them to fix it. A PROBLEM THAT I HAD FROM THE DAY I GOT THE THING!​

​So quite frankly I'm at my wit's end.​

​I hope someone here has an idea of how to solve this​

​Thanks in advance G Rolley :)​