My experience is that ISP wireless equipment sucks for signals. Mine is fine within 10 feet outside of that it drops off sharply. The best way to deal with this is get something else to generate a wireless signal that is much stronger. I do this with an old router and new software(aka firmware) on it. It connects wireless with my ISP router and is just a bridged repeater. But I am the "computer" guy in my family so I get old equipment given to me before it gets tossed so unless you have an old router sitting around, not the old one from your ISP, you will have to buy a bridged repeater.
I am not endorsing this product in particular
Not all ISP provided equipment sucks for wifi. The 2-Wire 3800hgv-b Gateway that ATT uses for U-Verse, will put out a signal, that you can see up to 150' outside of homes. Wireless-b & g will go farther then Wireless-N. But the problem is that if you have a lot of congestion, or multiple A/P's on the same channel as you have your A/P, you are going to have issues.
The problem is that the OP is a Virgin Media subscriber. This makes the second one having issues with Virgin supplied equipment. Since this equipment is for FTTC, there is not much they can do, but add another A/P as I stated before, to increase their coverage. See the following for the review on the OP equipment. http://www.theproductsite.com/blog/talktalk-huawei-hg533-router-review/