I always have bad signal

No I'm tired now every month I pay but no one can get me on my cell nr it is on voice mail because of bad signal and I want then to release me from my contract as I want to join a better network as I did report problem before and nothing was done about it and I can't even use my data on phone as signal don't allow me to I had to get wifi from someone else to help me so I want out of this contract thanks