OP, you will have to convince the school that you have had a long hard look at yourself and changed.
if you were my child, the bullying of other children would have made me so angry that you wouldn’t have had access to any electronic devices in the first place (unless required by school and then next to me). I would have taken the phone off you. It must have been extremely bad for you to be suspended.
With regards to the phone in the exam, it is probably impossible to prove that you didn’t use it.
again, if you were my child,
> with regards to the bullying: I would make you get involved with anti-bullying. I would find some way for you to volunteer or similar to make you understand how serious it was. I would also make you write a long letter to the person you bullied and apologise. And finally, I would have made you responsible for protecting the child you bullied against other bullies.
> with regards to the phone in exam, I would make you insist on re-taking the mock (or another mock) to show the school that you didn’t cheat and commit to not having a phone in school for the following two terms.
provided that you did the two things above, O would then do what I could to support you.