BBC, ITV problems in Spain

Hello, can anybody help me or give me some advice.

I have a good quality (80% SNR) with sky channels, MTV, discovery, etc

but getting a very low SNR on BBC, ITV, CBS, E4, etc channels.

I'm locked on the Astra 28.2 East using the cateye bouquet.

I am based in Spain, my setup is a 120cm dish.

Thanks