Guys, any application allow wlan file transfer?

File transfer from laptop to phone & phone to laptop?

guys, i got a problem, i dont know whether its a problem with DiGi or is it a problem with my fone, i recently sent my fone in for warranty, they changed my motherboard, and then for a while it was all good until a few days ago when my reception and data went crazy..

sometimes i can use 3G for about 30 mins then it stops working (altho states that its still connected) and then u can see the reception bar between 0 to 2 bars (normally its full).. then i tried switching to GSM, and then reception went up to full bar and data works again.

then this morning i was using the data on 3G and again, it works, but after a short while, it stops loading and reception goes down. Now my reception is at 2 bars and ppl seem to have trouble getting thru to me.

what should i do? it is a software, hardware or network carrier issue?

help really needed! Thanks.