A company with terrible customer service

I cancelled my membership at the end of the 2 year contract and I have emails to prove that, yet this company is still harassing me with different people calling me and no matter how many times I keep explaining my story, I get a different person to call me again. They have recently handed my account to debt collectors/ attorneys. I paid this company every single month without defaulting not even once, even though I have not stepped into their premises. I followed process to cancel and yet my account is still open