Not backing up whole albums

I'm having problems with your app. I turned on backup, and with a strong internet connection, (iPhone to PC), only 200/600 photos were backed up, and in random order. Yet it said on the PC that all of the photos had been backed up, but only a few were. I tried with another album: only 600/2200 photos were backed up, again in random order, again with the sign on the PC that the backup was complete. The photo transfer app on the iPhone appeared to be frozen. Please fix this problem- I paid money for your app and did not expect it to freeze. I was specificallytold that it could backup over 2000+ photos at once, which was the only reason why I brought it, and I am extremely disappointed that it does not work as you told me. Please help me to find a solution to this problem.  It isn't a problem with the internet connection, and both the PC and iPhone were left on (without going to sleep etc) during the transfer, with only the Photo Transfer App running.