range extending a Belkin F5D7630 ADSL modem/router/WAP

Has anyone else had trouble trying to extend the range of a Belkin F5D7630
ADSL modem/router/wireless AP?

I naively thought (reading all the advertising blurb) that a Belkin F5D7130
wireless AP/range extender was just what I needed. But no. A 7130 will range
extend a 7230 (cable modem/router/WAP I think?), or another 7130, and for
all I know most other Belkin products, but *not* a 7630.

Any suggestions what I do now? Buy a *second* 7130 and plug into one of the
7630's LAN ports (having turned off the 7630's radio), and use my currently
duff 7130 to range extend that? I'm a bit cross at the idea of sinking yet
more cash into Belkin's coffers when their promotional material should have
made this clear (in my opinion at least).

If anyone has any bright ideas how I should best proceed, I'd be very
grateful to know...
Other potential 7630 buyers should probably know about this. Why have Belkin
done it?

Thanks...
David