Debt collectors not reading their emails

This company sends out threatening emails with false information , they state that they have contacted you multiple times but don't read or react to correspondence. After I phoned them today the lady looked for my email sent almost a week ago and advised that she will look at the proof of payment, she then proceeded to disappear form the phone call, I held on for another 3 minutes but nothing so I ended the call as it cant take that long to look at an proof of payment.