I've just been reading around on this for you and it seems this is a very common problem with this particular brand of wifi card. The most common solution that seems to keep popping up is to install the actual MS Windows driver for this card using something called "ndiswrapper". I used to use ndiswrapper all the time back in the days of Ubuntu 10.04. But have found, since ubuntu 12.04, that it has become more or less obsolete due to improvements in driver support from Ubuntu. This particular card, however, seems to have slipped throught that particular net.
You can install ndiswrapper from the software centre and there are plenty of guides on the internet on how to use it.
I hope you can get it fixed mate, because I do understand there is nothing more frustrating that a wobbly internet connection.
Failing the above, one cast iron way to get your internet working is to use something called powerline adapters. These link up your ethernet card to your mains wiring system, via a standard plug socket, to your internet router, whoch is connected to your mains wiring by the same means. It's more or less as fast as standard ethernet cabling, but is a hell of a lot more convenient due to the mains wiring being already hidden and in place around your house. The only caveat to the above solution working is if your PC is on a different floor in the building than your internet router is on. This is becase it would mean the powerline signal would have to go though your electrical junction box to get from your downstars mains ring to your upstaris one. Unfortunately, there is too much electrical noise occurring at the junction box and so the signakl would get scramled. Thus, if you have a situation where your internet router is on one floor, but your POC is on anotehr floor (and so using a seperate mains ring, the solution is to run an extension lead form your router's ring mains to whereever your Pc is and then run your power line adapter on your PC to that extension. thus, ensuring that both your PC and internet router can communicate properly. Or, alternatively, simply relocate your router on the same floor as your PC if you have a telecommunications point on that floor.
A better illustration of how powerline adapters work is below:
I can personally vouch for these as I use them myself in my own home following similar issue to yours with my wireless card. In my case, the RTL8192ce.
It would mean spending about the same as you would on a new wireless card for the pair of powerline sdapters you would need (about 25 quid for a pair of adapters in the UK) However, their advantage is that they are guaranted to work as they directly communicate with your ethernet. No drivers or any other software required.
They sound too good to be true don't they....I certainly thought so prior to buying a pair. However, since doing so, I haven't look back