Asha 302 doesn't want to use WiFi

So I'm a user of Nokia Asha 302 and though I generally love the phone, one problem just gives me nightmares.
Namely, I can't do almost anything requiring WiFi. The only thing that works is the stock browser - if I want to use the built-in email client, it gives me "connection error, please try again later" prompt. If i want to install opera - same thing, I can download the package from the Ovi Store but as soon as installation starts, it requires my GPRS connection rather than the WiF that it's connected to and which is working.
I have WiFi set as defaut and always select it as the desired connection method when asked to but it just doesn't work. How can I force the phone to use WiFi for such tasks and not my packets which I have to pay for?
I googled my head off and found absolutely nothing. The onky method I found involved adding some custom configs like "my web" and such and even though I followed the instructions, it hadn't helped a bit.
Could someone please tell me how to fix it?
Go to Solution.

Setting the mobile APN manually might help so that the phone will use WiFi when available. Please check these links for the steps required:
Nokia Lumia 520 3046.0000.1329.2001 RM-914
Nokia Asha 302 V15.09 22-05-13 RM-813