Help and ideas pleeeease!

I currently have a three year old foster rabbit who has only ever been fed on cheap rabbit mix. Nothing else at all. I am having real trouble persuading him to eat pellets or hay. The only success I have had is moving him onto Rabbit Royale because I feel it is better than the one he was uses to.n at least he eats it all and is not selective!

As far as hay goes, he will pick it up, nibble a strand till it breaks in two and then drop it. I have tried toilet roll tubes, mixing his mix through it, putting handful on top of the cage so he can pull it down through the bars and leaving loads in his litter tray.

If anyone can give me more ideas to try I'll be really happy.

just a suggestion but what if you give them very little of what they're used to having plus very little of what you want to give them then gradually increase the good stuff?
mix it with the hay
i believe perseverance is the key with a healthy rabbit

Unfortunately he goes on hunger strike. Only managed 24 hours with him refusing to eat before I gave in and gave him more chudleys. He hadn't done any droppings in that time and I was really worried about stasis. How long do you think I could leave him?