macbook cant connect to new router via wifi

I have a late 2008 Mac Book (Model A1278) and I recently had a fibre optic broadband installed in my home (Hyperoptics with a Tilgin HG2301 router).

Since installation, I can connect to the internet via ethernet cable, but when trying to connect via wifi, it very quickly just says "Connection timed out".

After restarting everything lots and lots of times and changing channels the wifi broadcasts on etc, I managed to get it working once or twice, however, it was sporadic and now I just cant get it to work at all.

Other devices such as my iphone, ipad, 2 PCs, sony laptop, TVs etc all connect without any issues.

I can still connect to my old ADSL broadband on my mac book too - however this is due to be disconnected soon.

I have tried removing all wifi connections, restarting the mac book holding command, alt, R + P to clear the ram, I have completely wiped the mac book and reinstalled OSX 10.9.3, and nothing has helped.

Hyperoptics (my ISP) have checked all the router settings and cant find any issues for why it wouldn't be able to connect.

Can anyone please help me?