Block the bullies from contacting you. Contact your phone and Internet service providers and report what is happening. They can help you block messages or calls from certain senders.
It also helps to change your username, email, and cellphone number. Make sure you share your information with people who have no contact with the bullies. Check your friends' contact lists carefully. Are any of them friends with someone who may have ties to the people who are harassing you?
Understand that what they are saying is wrong and hurtful. Don't believe what they say or let their bullying make you think something is wrong with you. Remember: Bullies don't worry about being truthful. They just want to hurt you.
Let someone you trust know what is happening. They can support you and may be able to find a way to help.
Lay low and don't reply to the messages. Things will only get worse if you do. Plus, that is what the bully wants anyway: they want a reaction from you.
You should always keep a record of the bullying. Print out the harrassing messages and keep them in a file. If the messages are threatening, contact the police. You do not have to put up with this harassment, friend. Protect yourself.