Wild Bird Seed Mix

I've been buying a 12.5kg wild bird seed mix from B&M for a while now - the brand is Glennwood and it costs £5.69
As with most of these cheaper seed mixes they contain seeds to bulk up the bag, which the birds generally leave.

I was wondering if there are any other 12.5kg seed mixes that people can recommend, with better seed mixes that will all get eaten?

Thanks