Poor reception on phone and laptop unless I'm sitting next to my PC!

[#1]

My Plusnet signal isn't strong enough to go through walls/round corners in my ground floor flat.  I've tried a range extender from Maplins but that was a disaster.  My Thompson router is about 5 years old; would a new one improve things?  Or can anyone recommend a range exteander which isn't too pricey and which does the job without causing major havoc to my PC?
Thanks in advance.

[#2]

Look at the homeplug devices. I'm currently using a pair and I'm quite impressed.
It does mean plugging your laptop or whatever into the other end but you could use one at the other end of your flat as an access point and extend your wireless that way.
How big is your flat ? Are the walls solid brick ? If it is a relatively small flat, a new router may provide better wireless.

[#3]

I use this pair of homeplugs very successfully:
http://www.solwise.co.uk/net-powerline-pl-500av-pevw-kit.html

[#4]

Homeplugs go much slower than the rated speed.  You need at least 500 rated ones for FTTC, unless you have slow FTTC and very clean mains.
I got Zyxel PLA4201s; you can now buy a pair for under £20.  They work quite well when they work; but I have just had to have a second replaced, one failed very soon and one after nearly 2 years.  3 year guarantee which Zyxel operate pretty efficiently.