At three months old the breeder knew exactly that they were selling you cockerels. No wonder they ignore your attempts to get in contact.They were about 3 months when I got them from a local breeder. They had next to no tail feathers in so I couldn't tell based off that and just noticed after I saw one attempting to mount my hen that their feathers looked very rooish. I contacted the breeder and they ignored me.
You can try to resell the birds to at least get some money back. Or fill your freezer.